I've taken Paxil and noticed the weight gain. All I can recommend is a constant awareness of the amount of calories consumed and more activity.
I am now on the new antidepressant Lexapro. It seems okay so far and it is supposed to be weight neutral. In other words, not as many gain on it.
I have to admit that I am not always conscious of how much I am eating. When I kept a journal of calories and exercise I did much better and lost 60 pounds, too.
Good luck to you and glad Paxil is helping you. That's great.