Pregnancy scare!

I hooked up w a dude on the 10th of March. He came into my mouth but I spit it out and while i spat it out, he was cleaning himself (not sure how well) , after that, I sat on his lap facing him. I was wearing leggings and underwear but I’m scared that the semen seeped thru into my vagina. I’m stressing out a lot, I’m a couple days late to my period and have been having cramps and constipation and nausea, could I be pregnant from this?