What Causes Bleeding Soon After Having Unsafe Sex?

i had sex early sunday morning, and the condom broke. then the next day around 12, i got my period but it only lasted 3 days. It was time for my period to come, so i knew i was gonna get it. I just want to know if it was my period or if i can possibly be pregnant. i did some research that bleeding from implantation is 5-10 days after conception.