Feeling down over my weight.

Hi. My name is Christina. I'm 25, 5'4", and 191 lbs. I'm four weeks pregnant. I haven't always been this heavy. I have bipolar disorder and a side effect of my medication is weight gain. I started out a year ago at 145lbs and have been trying to lose weight since I gained almost 30 lbs in three months. I'm not unhealthy; I eat well and exercise daily, but the weight just keeps piling on. I can't look at myself in the mirror or even undress without wanting to cry. I'm scared that my weight is going to hurt my baby. I just feel like a whale and I'm not even that far along. Hubby keeps telling me that I'm fine and not to worry, but I can't help it.