When I first went on Depo (ages ago) was also when I experienced my first real weight gain...think I packed on something like 15-20 pounds in the first year or so (eek!). I have never gotten back to that point either
Took a long break from the shot and got in better shape, but have now gone back on the shot for the convenience of no periods and it really helps even out my mood swings. While I have not gained, I am fighting like hell just to stay where I'm at. Have thought about taking another break from the shot just to let my body get cleared out of the chemicals and make a run for my goal weight. Good luck!