Depo, 7 weeks PP. But....

I got my Depo shot 4 days ago. I had a baby 7 weeks ago. I had sex 3 times before 6 weeks PP, he pulled out. The doctors office pregnancy tested me before I was able to get the shot, it was negative. But today we had sex & he came in me... I know it was stupid. But im scared of getting pregnant again, since I just had a baby. It's too soon for me. What are my chances?