The therapeutic approach to BPD can't be rushed. It's a process.
My T does not diagnose. The only reason I know my diagnosis is that I read a lot and when I read "get me out of here" and "I hate you/don't leave me!" and "Understanding the Borderline Mother" I felt the diagnosis might apply so I asked her. She readily agreed and said she had thought that very early on.
Trust the process, my T tells me. I do. I have been in therapy for a year and 9 months, recently beginning twice weekly sessions. I do feel better, although I think it took a while for me because I have a hard time talking in session.
Trust the process.