A few things...
1) If you have all those diagnoses, then you do have a bit more than most to work with, and it also hopefully means that you are regularly consulting with a mental health professional of some sort and keeping you family in the loop of how you are doing and when things get too far out of control and unhealthy, as that would seem to be of great value.
2) I can't help but think of some of the more centering, grounding energetic things I have heard people talk about, such as found at AYP: perhaps those who know these better will chime in, would be of value to you. I bet Tai Chi or something in that vein would be useful.
3) I recently watched a nice TED talk by a person who knows a lot about the Dark Night and also clinical psychiatry:
TED talk and I found her advice about you reinforce what you think to be spot on and applaud your continued efforts to change the habits of negativity: not easy a lot of the time, but so well worth it.
4) In that vein: have you looked at CBT?
Just my thoughts this early morning. Thanks for posting your questions and concerns: they are actually pretty common in these circles (and actually all circles) and not talked about enough.
Daniel