You sound like me, I gained weight too and just went on another drug that my doc says 'might' cause me to gain weight. The things is, we can help ourselves in this. One doctor told me that the reason we gain weight is because we feel better, we are more relaxed in general and so give ourselves permission to eat.

And we eat the wrong things
Or we don't exercise even though we know it is critical to maintaing/losing weight.
So I would suggest to you that you try to control what goes in. Augment that with a TON of water. Go buy sparkling water to drink with a little lime or lemon in it if regular water gets boring. Brew iced tea and drink that to mix it up. The first thing you do when a hunger pang strikes is drink a glass of water.

Eat Normal(?) small portions and do not allow yourself any soda or foods that you know are a problem. (crackers, chips, ice cream) We all know what our food issues are, but I am here to tell you we can support each other to make the right choices and help ourselves.
Best of luck to you with this and with feeling better!