<p>Congratulations for facing your issues and wanting to change.
I agree with the suggestion of mental health, but therapy, not drugs.
Another good thing to try would be Overeaters Anonymous. It is a twelve step program that guides people toward healthy eating and living, and also provides group support.
And, exercise! Start by walking for an hour a day, or swim. Drink water frequently while you exercise. You will be able to build up your exercise tolerance as you lose weight.
You should be losing one to two pounds a week. Any more and you risk doing it in an unhealthy manner and gaining it back more readily.
I have to admit that when I first saw the title of your post you were going to say that you took Depo-Provera. This drug works well for birth control but also works well for packing on the pounds for some, not all, women. I personally think that the risks outweigh the benefits, as alternatives for birth control exist. I have to wonder why it is still on the market. Stay away from this drug!
Other drugs that are causing a lot of weight gain these days: so-called second generation antipsychotics, which are also being used off-label for a number of other behavioral issues. If they are absolutely necessary it is one thing, but sometimes there is another way.
Good luck!</p>