First off, I just want to say that in my opinion, being of healthy mind is more important than anything else...weight gain included. I know how low I got before I received treatment, and I'd gladly gain weight if it meant I didn't have to go back there.
That being said, I COMPLETELY understand your fear of the weight gain, especially because you worked your booty off to get to where you are now. I think you'll find commentary about weight gain for every kind of anti-depressant. I started on Celexa a couple years ago, and have noticed a weight gain since then, but that could be related to eating crappy food, getting older, etc. A couple months ago I switched to generic Prozac, and noticed that it's even harder to lose weight now (working out religiously, eating healthy, etc). I made the decision to switch to Wellbutrin because I've heard it has a lower incidence of side effects, including weight gain and lowered libido, etc. So I'll know soon hopefully how that goes (haven't talked to my doc about it yet).
Best of luck getting to a healthy, happy place...and not having to gain tons of weight to stay there!!!! You've got a great support system here.