Oh..I just saw that your gender on here is Male. Do males have menstrual cycles? Hm? Or was that a mistake..? lol
I took Depo one time and thereafter had constant spotting and irregular periods for over an entire year. I would never go with Depo ever again, personally, and would never recommend it. I gained over 40 pounds also within that year! Just giving some personal experience so hopefully no one else will have to go through what I did. But as to your question of what could have caused you not to see your period still after...that's what Depo does...it screws your body's balance up. It'll go back to normal...can't say when...but mine took a while.