What Are The Side Effects Of Depo Provera Injection?

I had a depo provera injection on September 15th 2010 after an abortion, which I deeply regret.. I was due to have another injection at the beginning of December 2010 but I didn't because I want to have a baby. It's now February 3rd 2011 and I still havent had a period. In January 2011 I had a bit of brown discharge for a few days but nothing else. When will my period return? I so desperately want to try for a baby. Please help.