Chance of pregnancy?

I had unprotected sex on the 13th, but I’m not due to ovulate till the 19th. He came inside me in which I didn’t mind cause we figured theres little to no chance in getting pregnant, but after further research apparently sperm can live inside of you? I had no idea and I’m pretty old too, I wish back in highschool they couldve taught me this. I’m not really worried, because me and my boyfriend arent actively trying but we also wouldnt mind a baby. I just wanted to know what are the chances in this resulting in pregnancy? Is it quite low or high? Should I even be worried? Or do I just sound dumb thinking I could even be pregnant?