I have dealt with depression since I was a teenager, too. During my first pregnancy I went to the doctor and she suggested that I go on meds (I think I was about 5 or 6 months along). I was very hesitant but I did it. I'm sorry I can't remember the name of the med, but it made life bearable for the rest of my pregnancy. Since then, I've been on meds continually (I started meds in 1999). My psychiatrist had encouraged me to stay on my current meds when I was trying to get pregnant again, and during my second pregnancy in 2005 I had no problems whatsoever. I've also heard that anti-depressants during pregnancy can actually increase the development of the fetus' brain. I don't know how true that is, but it is cool to think about! Right now I'm on a combination of Wellbrutin and Prozac, and it seems to do a good job keeping me steady. If I were you, I'd consider taking anti-depressants because your depression and stress can negatively effect the baby, too. Maybe look into some of the "older" drugs, like Prozac - more studies have been done on those so sometimes doctors feel more comfortable with prescribing them. Also, I remember speaking with my psychiatrist about anti-depressants during pregnancy, and they have reference guides that rate drugs and their risk to the baby - like A means little to no risk, B means slight to medium risk and take if it is necessary for the mother, and C means no way! Also, my psychiatrist has started me on Vitamin D3, 2000IU's a day as well as 800mg of Folic Acid a day. Being so far up north, our bodies stop producing Vitamin D from the sunlight in September and many of us can be affected by the lack of Vitamin D.
I know that there is a lot to think about, and the health of your baby is high priority, but so is your health - both mental and physical. Your baby will not benefit as much from a severely depressed, stressed and unmotivated mother as it would from a more stable, somewhat happy mom. Also, I think that it helps with hormone changes after birth and the drugs can counter the effects of post partum depression. I wish you luck and I hope that you are able to make a decision that is good for both you and your baby.:)