Just to follow up on this....
I spoke with my therapist yesterday and he explained that it is never cut and dry and BPD is closest because of extreme reactions to internal conflicts.
I asked about "Fear of Abandonment" (which I don't have) and he said you can replace this with just "Fear" (which I do have, in spades). I also don't have unstable relationships, self-injury, etc.. but he said none of these are central to BPD.
As far as my dissociation (I'm dissociated a good part of the day and have been since I can remember), he said extreme dissociation, depersonalization, and identity confusion is also part of BPD.
He has also referred to my symptoms as Complex-PTSD.
I actually feel a bit better about this now. While it would be nice to have a "neat" diagnosis in which everything fit, I can live with a BPD/C-PTSD diagnosis.
My main desire for a diagnosis was being able to learn more about the condition on my own. I'm able to do this with BPD and PTSD/c-PTSD books and information.
Not all of it applies to me 100%, but I can discern which are applicable and which are not.