I suffer from depression as well, although during this pregnancy I haven't been on any meds and am doing much better than usual. The hormones must do weird things to different people. I think my body was already strange so pregnancy hormones balanced it out.
Anyway, try to remember that it is temporary. Your hormones are out of whack and you have a right to feel this way. There isn't anything wrong with you, you will be a great mom, and everything will work out. I know it's really stressful and I hope that they balance out soon. I'm sorry that I can't really say anything that will actually help, but just realize that this is normal. Concentrate on the fact that your boyfriend is supportive, caring, and optimistic. Good luck!