I didn't realize this, but apparently it's been a known fact that thyroid disorders and mood disorders tend to go hand in hand, however, no one thought to try to pair thyroid treatment with BD, until this new research was conducted.
They found that (to quote from the article) "thyroid supplementation in women with rapid-cycling BD who tested positive for antithyroid antibodies was associated with a reduction in mood episodes and significantly reduced manic and depressive symptoms."
http://www.medscape.com/viewarticle/881014
That sounds pretty promising. Levothyroxine (T4) is apparently a fairly safe medication, even for pregnant or breastfeeding mothers and side effects are usually only a result of using incorrect dosing.
Would you be willing to add levothyroxine (T4) to your medications to see if it helped?