I just came across your post now...
My last injection was Aug 28/08, and I still haven't had a period. I have read up on the process, and apparently it can take anywhere from 6-18 months to return to normal mentral cycles, and sometimes even returning to fertility. Have you had any luck since your last post? Please do keep me up to date on when you return to normal, as I am patiently awaiting mine.
im having the same problem. i started depo in august of 07, my last period was oct of 07. and my last depo shot was feb. and still no period!