TTC / Depo Shot

I would like to know if any of you ladies were ever on the birth control shot? I used in my teens, got off it then had two children. Then went back on it for 1 year, and now ive been off it for alil over a year now. Ive heard its harder to get pregnant if you've used it. So im wondering if any of you are having the same problem? Ive gone to my doctor and she told me to keep trying.