Pregnant? Or not?

Hey guys a couple of weeks ago I had sex with this guy and we used a condom but half way through it, it came off and I'm not sure if he 💦inside of me. Two weeks after that I got my period and now I'm waiting for it to come again but my boobs have been unusually sore lately, not like they usually feel when I start to get my periods. Is it possible to get one period once after this has happened and actually be pregnant? Or not?