Depo provera is notorious for staying in your system longer than any other birth control once it is stopped. It can remain in your system for 12-18 months. Some women luck out and can get pregnant quickly, other women take over a year.
Unlikely u could be pregnant from that encounter. Esp if you were taking the shot as directed. Stranger things have happened tho so take a test.
I agree with Quinns momma!! It took me 6month to get pregnant after stoping the depo.