There's no way to tell how your body will react to going off the Depo shot. However, if you've had less than three Depo shots, you haven't given it enough time to work- nine months. For some women, one shot is all it takes to completely eliminate their periods. In my case, my periods stopped shortly after my second shot.
It took me about eight months to resume regular periods after going off the Depo shot. (I don't count any intermittent spotting that occured.)