Off depo shot for over a month now, could I be pregnant?

I would say not. I took Depo, and even after 1 shot, the hormone stays in your system for quite a while. My doctor told me that after a shot, it is completely effective for 3 months, but it can stay in your system for up to 6 months. One of the side effects of Depo is no period. Typically that doesn't happen after just one shot, but hey, anything is possible. If you have a test, take it to be sure, but I had all of those symptoms, plus weight gain when I was on Depo.