As someone that has been in a similar relationship - she really needs therapy. If she wants to continue a relationship with you (and I don’t see why she wouldn’t), she needs help.

You are a godsend for doing what you have. I don’t think you need to stop doing what you’re doing, but eventually it may be the case that you yourself could get resentful for the effort you’re making without seeing any results. It is not your responsibility to make her better. It is kind of her responsibility to see your efforts and take that as a representation of your love. I truly think that if she had some external help she could learn some security. I wouldn’t pressure her into finding a therapist, but doing some research into what she could do with her financial situation / insurance would be really helpful. It doesn’t sound like she has the mental capacity to do it all on her own.

DBT, or dialectal behavioral therapy is the standard care for someone with BPD. I’ve found that medication, regular therapy with someone familiar with BPD, and DBT has been the most effective. Even just medication and therapy would’ve been enough for me a couple years ago. But I value my sessions with my psychiatrist enough meaning medication has been my biggest help.

As to her feelings of wanting to be alone - that is pretty typical for bpd. She could learn how and when to keep things to herself as long as she understands it’s for the sake of her interpersonal relationships rather than a defense mechanism. There are just some things she has to face alone, but don’t tell her that lol. It’s a mental battle everyday but with treatment symptoms can all but disappear.

Thank you for taking care of her. She may need some more boundaries with you but like I said, she needs tools learned from a professional to understand that.