Hey, so this is a late reply but having seen it and been in the situation I thought I would chime in.
I initially discovered similar symptons and also more extreme ones, e.g. she told me there were times in the past she had self harmed (and still at times wanted to) and had bulimia. I cared for her greatly and continued the relationship and ended up being very much in love with her. When she was on good form, she was incredible to be around but in her bad moments which in time became more frequent it became unbearable. When I first told her I thought she might have BPD, i was as expected met with hostility and it was an issue however it was something that she then told me her father had also had and when she saw someone they diagnosed her with it too. It did help us and her to have this diagnosed as it meant it could be researched, it had a name for her benefit and it didn't cause future arguements.
If you want to be with this person, you need to realise you have to be able to always put up with episodes in a calm and gentle way, you cannot lash out or get irritated or lose patience because not only does this massivley escalate the problem but the person will remember is and it spirals into later episodes. You need to realise that they cannot help the way they are under these episodes and it's not their fault, and that it does not define them. However you cannot be a doormat. You must set ground rules from the early stages for yourself. It's a condition that does eventually get better in time (statistically) and I can say therapy massively helped in our case. An example might be that at a certain time you must be allowed to "leave" for example a phone conversation by a time to allow adequate time for sleep. In my case my girlfriend had a fear of abandonment which meant when she was in an episode from early days we could be on the phone until 6am and I would be forced to pretend to fall asleep to end the conversation or it would simply not end and this helped neither of us. Setting rules later on helped us.
For me, it wasn't worth it. The relationship went on longer than I should have allowed and it ended up with us both being hurt. I did not have the patience for it and I made episodes worse. It definitely requires a very specific kind of person to be able to deal with BPD I believe and you must think if you one can commit to that and two whether you're willing to make the sacrifices that will inevitably come while being such a young age. It is a commitment. I wish you the best of luck.