confused?????

If you have a period and didn’t have sex after it, you can’t be pregnant right?

Ik it’s a dumb question but i’m a worrier, my boyfriend and i had unprotected sex for almost two minutes, he didn’t come or anything. two days later, i got my usual period but it was a day shorter (6 days) . It’s been about 4 weeks since we had sex and now i’m waiting for my upcoming period. I’ve been extremely moody, irritable, and bloated with a bad breakout lately. It’s probably just pms right?

Sorry for the dumb questions, I never got good sex ed and the internet scares me.