One thing you might ask your doctor if you can try is stopping the
seroquel and starting
abilify in its place.
Abilify is approved as a monotherapy or adjunct treatment for BP I, and is also approved as an antidepressant add-on, so if depression is your problem, it might work.
You could also try other mood stabilizers like depakote, which has pretty good antimanic effects, or tegretol, or lamictal if you mainly get depression. Also, have you ever tried lithium?