Long term consequences of Depo Provera?

Patient: Hello, I have been on the Depo Provera shot since I was fifteen years old, I am now twenty and have been completely without a period for around four years. I began taking Depo because of ovarian cyst problems that a doctor spotted.I already understand the side effects of getting the shot but I am wondering how safe it is to take for five years or longer and what effect taking it so long might have on reproducing in the future?My OBGYN highly encourages me that there are no issues with me continuing to get that form of birth control since I am only twenty and that I should continue on. What do you think?Thanks.