I also have bipolar and take Trazadone and Topamax, I quit taking them the day I found out I was pregnant! It isn't worth it to me, I know that the medicines are Class C and like you said the benefits could outweigh the risks, but in this case...I don't want to have to worry that the medicines I take could harm my unborn baby. I wouldn't want to have to think that something I took, hurt my baby. I have also tried to commit suicide, in 2001 I OD'd and was in the ICU for 2 days. This is a personal choice for you concerning the medicines. My sister took Zoloft while pregnant, it is one of the safer ones.
Good luck with whatever you choose, if you want to talk ever, you can email me.