Pregnancy and Depression

On a good day, I'm mildy depressed when I'm not pregnant. I dont take any medication and just try and deal in the best way I can. But the guilt of possibly affecting my little girl and her chemical makeup really wears on me sometimes. It gets frustrating hearing from others telling me that being sad or angry isnt good for the baby, which makes me feel even guiltier. So do any of you ladies battle with depression and how do you cope with your emotions being so heightened and the guilt that comes along with it