Can I be pregnant after a first child?

Hi. My name is Aubrey. And Im with my boyfriend Monte. Monte and I have been dating for 2 year and have a kid. We were both 17 when our baby boy Aden was born on March 31, 2011(: A week after my post check-up, I decided to get on BC, because we are both still in high school trying to finish. Well, I had gotten the Depo Shot on May 26, 2011. A week or so later, my boyfriend and I had sex with a condom, but for a strange reason I think it broke! He said he came about 3-4 times and Im scared I might be pregnant again): I was bleeding during this time, but Im not sure if I was ovulating. Is there a strong possibility I could be pregnant again?