Thanks for sharing, appreciate it can’t always be easy. However, the best suggestion and most helpful for all involved would be to do that one thing you’ve already picked up on, which is to Talk to her!!!
Find time to sit down, just the two of you where you are not tensed, stress or having an argument. Be open, honest and share how you feel both around what you want and your expectations and how her reactions and actions make you feel. Also, give her the opportunity to share her thoughts and feelings on the areas, and to be open and honest. It’s important neither if you raise your voice or get into an argument, but listen to each other. Or if one of you does, realise that it’s not helpful and purely emotional and don’t react to it.
It’s important to recognise both of you had separate and different upbringings (based on what you’ve said). It might be a case you overall had it easier than her, or at least that the way she sees it. It could be that your parents showed more or different attention to her. It could be a lot of things that have ultimately led to the current relationship you have, so good for you both to share your views and side of things.
If you can, also share what kind of relationship you’d like and want with her, and see her aims to for this. Things will not change overnight, or they might not change at all but at least both of you will know where you stand.
The constant arguing is both of you holding the truth and your feelings, and maybe repressed feelings and memories without a better outlet for them and that’s why the things said, get said.
Don’t be afraid, if you would like a better and stronger relationship with you sister then being honest is the only thing that will ultimately achieve this so take the first foot forward. You’ll feel better for it too, and not worry about it really anymore.