Hello there, Monlapin, and welcome to BPD Family.
You have indeed come to the right place for help... .especially on helping yourself. That is the key - self-care which gives you the strength to face and deal with whatever comes your way.
It is sad and maddening to read that the mental health team your daughter has seen for 3 years will not communicate with you. This should be a team effort!
You write... ."Now she goes from 100% with me for months, to 'I hate you and do not want to speak to you'. Boy, do I relate to that statement. So many times I would be basking in the wonderful feeling of thinking all is in the past... .then in the blink of an eye I (her Mom) was her nemisis... .the cause of all her problems. Literally, I would be stunned, left trying to catch my breath and wracking my brain to figure out what had happened to bring this on. The first book I read was "I Hate You, Don't Leave Me" and gotta say, I sobbed when I read it because it was so validating.
I am one of the older parents participating in/on this forum, the tumultuous, roller-coaster relationship with my daughter spanning 40 years... .me playing the role of victim to her tole as bully. Coming on board here was a game changer for me... .and realizing it was ME who had to change. I had to tell myself... .and then believe!... .that I had done the best I could for her... .but not for me. I was a mess!
I so urge you to do your homework here... .all the info to the right

and with links to more. On top of that, documenting/venting your progress by posting here can really be soothing because you know you are sharing with others who are nodding when they read your posts. We learn from each other here. What works for one may work for another... .or may not... .but a work-in-progress is better than no work at all.
I'm sure you can conjure some memory from the past when a change has occurred in your life. Unless you decided to walk away, you pretty well had to adapt and change yourself. This is the effect that you can have upon your daughter. (See Lesson 2

"If your current approach is not working - change it>".
Hope to hear more from you, Monlapin. Lots of success stories here... .but I've learned that the look of "success" doesn't always turn out the way I envisioned to be... .and that can be okay, too.
Huat