First of all, I was on the Depo shot for the same diagnosis for 10 years and just stopped it this Monday. You need to speak to your doctor about the side effects of the Depo Provera such as bone loss, weight gain and acne. I didnt think I had this problem until I broke my fingers the other day. The Depo Provera shot is only recommended for use for 2 to 3 years, but no longer than that.
Bleeding could be caused by irritation, could be a ruptured cyst on the ovary or cervix, or you could just have what they call "breakthrough bleeding". Just because you are on the Depo Provera shot does not mean that you cannot and will not have a period or breakthrough bleeding. If the problem persists, you should call your OBGYN. Actually, you should call them anyways and speak about the Depo Provera shot and ask them for something to stop the bone loss. Please dont be like me and think that it will not happen to you, because it will. I had to learn it the hard way.