How do I know when it's not worth it anymore?

I have no idea how to start this, so I'm just gonna jump straight in.
I am 19M, she is 19F. We have been dating for 1 day short of a year. Since, no joke, 00:01 January 1st this year, we have been arguing on and off consistently. It's so incredibly hot and cold and we have had major arguments over text and in person. Some of the stuff we argue over is so stupid, and it spirals out of control. Other things are serious, where we fundamentally disagree on something and it is becoming a massive problem. One of our biggest issues is that when we argue, I want space. I want to take time away, go for a walk etc to calm myself down and come back when I'm calm. She wants to sort it out immediately and doesn't like leaving things on bad terms or sleeping on bad terms etc, whereas I am completely fine with streching it out if it means I can step away and have some time away from her. This causes major issues as we fundamentally handle conflict in opposite ways. She also recently made a massive mistake, which she did give me space for, but she didn't see it as a big of a deal as I did. She's happy to give me space when its her mistake, but says I need to compromise more and talk things out, especially when its my fault. The point is, for many weeks now, we have argued pretty much every day. We have had 2 good weekends together in person though. There's just things she says and the way she thinks that makes me think it's never going to work long term. Some of the opinions she has on certain things I consider to be toxic and unhealthy, and vice versa. The arguments are so sh!t. We're constantly at each others throats and ****ing each other off. Yesterday, she said something which made me blow up and ignore her for the day as the last thing I wanted to do was speak to her. I also said some unfavorable things, but so did she. People say things in anger. Anyway, she says I've hurt her over the past few days so much that no matter what I say she can't get over it. Does anyone see what I'm getting at? Constant arguments, disagreeing fundamentally over things and lots of upset days and nights for both of us. We also had a rough patch where we argued nearly every week towards the last 3 months of last year, although that was less serious stuff and more "I made a mistake or overreacted and im sorry, lets move past it". She lives about an hour and 10 drive away at uni in nottingham, and I do a degree apprenticeship in york which I commute to every day from doncaster. Distance is fine as we see each other every week. She says I've changed recently which I have, I've become a lot more aware of important things with myself and prioritised myself more, this comes across as a lack of care towards her. I personally think that ones #1 priority, relationship or not, is ones self. I think my nutrition, sleep, gym etc is more important than seeing her. She wants to be my #1 priority and its starting to feel like im in for a life of worship and slavery as opposed to happiness. Just to be clear, she doesn't want me to not eat to see her or anything. It just feels like we value things slightly differently. All this aside, she's an amazing girl. I truly find her extremely attractive and she's a really kind person - training to be a nurse and all . I've been in a similar situation before with my ex, we were together for 1.5 years and towards the last 6 months I was ready to leave but didn't. It was very VERY VERY toxic and looking back I wish I'd left earlier, or yk... chucked her out of a 7 story window . ANYWAY. The thought of breaking up with her really hurts me, but I don't know if thats the feeling of not having HER... or just the feeling of not having ANYONE anymore. I know because i've been in this predicament before and it was a case of being worried about not having ANYONE. It is our 1 year anniversary tomorrow, we have a holiday booked to tenerife in april, and are on the borderline of booking another in august. My question to the good folk of TSR is: How do i know when it's not worth fighting for anymore? I also don't want to leave prematurely because of lust. I am a VERY loyal boyfriend and have never given her any reasonable doubt in that regard. However, my eyes have been wandering recently... the grass always seems greener on the other side, until it isn't. I don't know if i'm looking for a new home because mine is burning, rather than ringing the fire brigade That being said, I'll never cheat. If we did break up, I wouldn't be getting over her by getting under someone else, I'd continue my life as it is now and focus on myself even more than I already am. I go to the gym 5-6 days a week and I'm looking to start tutoring GCSE and A-Level Maths to eventually prosper into my own business alongside my degree apprenticeship. I'm not a man-****, I genuinely never had wandering eyes before all these issues, I do want it to be her though.. I just don't know at what point we cut our losses and stop hurting each other for the better. Are we at that point? I genuinely don't know.
Appreciate any help, kind internet strangers. Sorry for the rant.

To elaborate - if you've got fundamentally different outlooks on things that are important, it's unlikely the arguments are going to die down. Some people are just not meant to be together and that's okay. It doesn't reflect badly on either of you, if you figure that out.

Yeah, I'd have to agree that this doesn't sound worth pursuing any further.

It has only been a year, you don't see each other all that often, and yet you're bickering like a married couple who have been together for 7 years and have spent the last 6 months cooped up together in quarantine.
At this stage in the relationship, given the fact that you only see each other every other week, you should still be in the "I can't wait to see my girlfriend" phase.
The fact that you're not, speaks volumes.
Sorry my dude, I don't think this relationship is going to stand the test of time. You don't sound compatible long-term.

It has only been a year, you don't see each other all that often, and yet you're bickering like a married couple who have been together for 7 years and have spent the last 6 months cooped up together in quarantine.
At this stage in the relationship, given the fact that you only see each other every other week, you should still be in the "I can't wait to see my girlfriend" phase.
The fact that you're not, speaks volumes.
Sorry my dude, I don't think this relationship is going to stand the test of time. You don't sound compatible long-term.

I'd give nyself a deadline, the holidays booked and paid for and only a month and a half away so use that. See if the issues you have resolve by then, if not then you know what needs to be done

First, please use paragraphs next time. It makes things difficult to follow.
Second, you seem to be extremely unhappy in the relationship but afraid to be alone. Hence, it is better for your sanity to leave before any violence creeps in.
Finally, you have to critically assess what’s causing the arguments. If it is fundamentally different value systems, you should move on. If it is petty s*** then maybe you and your girl should work out a compromise.
If she has cheated on you, please focus on yourself, big man.
Good luck

First, please use paragraphs next time. It makes things difficult to follow.
Second, you seem to be extremely unhappy in the relationship but afraid to be alone. Hence, it is better for your sanity to leave before any violence creeps in.
Finally, you have to critically assess what’s causing the arguments. If it is fundamentally different value systems, you should move on. If it is petty s*** then maybe you and your girl should work out a compromise.
If she has cheated on you, please focus on yourself, big man.
Good luck

Go on the holiday you've booked in April. Do not book any more holidays with her.
After the holiday it would be fine if you broke up with her. Or fine if you continued to see her - if your relationship is back on track.
At the moment the 2 of you are incompatible when it comes to conflict resolution. If you can change yourself between now and April so that you are compatible in this area, your relationship may have some chance in the long term - depending on a few other things. If you don't change, and she doesn't in this area, then the 2 of you have no chance of a happy long term relationship.
You're being too perfectionist. Be more pragmatic.
It doesn't matter if the 2 of you don't agree on plenty of things. The inconsequential stuff. Or stuff where there's work arounds. Such as favourite TV programme. Taste in foods and drink.
There are certain core things where it is essential that you are in accord: eg number of children desired. And for those things, if you're not compatible you should go straight on to dumping her, instead of going through the trying to change her stage before dumping her.
You're taking things too seriously and too intensely. Love is predominantly light. It's not dark and heavy.
Your commute from Doncaster to York is ridiculous. Get some digs in York. It's a great city.
Give her one big sincere apology.
And focus on you being a lot lighter, more positive, more enthusiastic, more joyful, more jokey, more flirty towards her.
Tolerate her difference of opinions. Tolerate her flaws. Nobody's perfect.
Even if you decide to dump her after the Elevenerife holiday, it's still worth you trying to change now, so that you behave a lot more like an attractive man, so that your next relationship has a lot more chance of success. Due to your newfound good habits.

Good point. Do you have any idea how to handle the following holidays?
For context:
June 25, Mums holiday.
August 25, Dads holiday.
I said no to her mums holiday because it's too expensive.
I said yes to her dads, we were planning to bolt on an extra week after that in a different city in Cyprus after the week with her dad so that we got 2 weeks for the price of 1 effectively. Sounds great, but August is a long time away and I don't know if I want to commit to that.
My stomach curls up typing that because I genuinely thought this would be my girl through thick and thin, it hurts man.

I mean I wouldn't April is enough time to see if you can sort it out, things might likely come to a head before then just because this seems very emotionally charged. If you guys haven't got it sorted by the tine your back from the holiday

You're probably right, I just don't know how to break the news to her. She will just say "break up with me now then".
A lot of the recent issues have been from her saying I'm not trying for the relationship etc even though I feel like I am. Maybe I'm mentally past the point of no return... I don't know.