Getting pregnant after using the depo shot once

Cindy
I got my first depo shot once in December and was suppose to go back in March for my next one but didn't it due on the 9th but wasn't completely done till the 17th it's been about 2 to 3 weeks since it and I haven't used any type of birth control me and boyfriend had unprotected sex on 3/23 and 3/24 so he came in me could I get pregnant?