Hello,
I think that subtle lights and Pastel Kitten described BPD very well. I'd just like to add a couple more characteristics ~ because we don't all have the very same qualities.
I am an extremist. I either LOVE or HATE: people, things, music, or qualities. And I do jump around on that list myself. Sometimes, I hate grunge (or whatever). Then, I meet a decent person into that sort of thing, which entirely changes my point of view. Suddenly, I love grunge (or ___), and I go into it completely! Some time passes, and I change again into something totally different.
For myself, I can say that I have no idea who I am. People always say that you have to please yourself, you have to be true to yourself, etc. I say that I have no idea who in the heck I am ~ and I never have. I've been chasing whomever I might be for as long as I can recall!!
Personally, a sad effect (that I've noticed recently) is that I don't throw every little bit of trust into any of my relationships anymore. Even though I try .... I just can't do it. I hold back an important part of my core. Trust, maybe? I will not allow myself to completely relax and just "be". {Maybe this is a PTSD thing though, I'm not sure}
((hugs)) to you!