I think it's okay to go in and say, "I read about BPD and can really relate to a lot of it," or something along those lines. That's not dictating a diagnosis, but giving the T some information about yourself that may be valuable to him in getting to know you.

I am really very bad about self-diagnosing. Last week, I was convinced I had Aspberger's Syndrome. When I showed the test results to my T, she just rolled her eyes and said, "I'm going to throw your computer away."

So there's a difference in approaching something as shared information vs. self-diagnosis, imo.