I need advice.

So I js need some advice, I’m 15. Me and my bf had un protected sex 2 days ago, he didn’t cum in me or anything (Ik you can get pregnant off pre cum that’s why I’m worried) my period is supposed to start tomorrow but I’ve been so stressed about this because I’m so scared I might be pregnant that I’m afraid I’ll delay my period jus by being stressed bc I do that sometimes. So idk what to do. I’ve been freaking out and just hoping for the best. I was in my luteal phase, and Ik that’s like the lowest chance of me getting pregnant. from what I can find it’s only a 4 out of 100 percent chance I get pregnant right now. But it’s still possible. So I don’t know.