depo shot

My boyfriend and I had sex before my period and I take the depo shot and he had a condom on and he pulled out before he came and then layed down on the towel we had on under us and then I used the towel to wash my self off a little bit then as soon as I was done doing that I went to pee. What are the chances I could be pregnant ?? because I still haven't got my period and I using spot or get my period from the 25 - 5th of the next month..