Am i pregnant?

I’m 18 years old and on Saturday into Sunday, I had sex for the first time with a close friend(his first time as well). Today is Wednesday.. but since last night (Tuesday) I’ve been feeling quite nauseous, my stomach hurts a little, and it’s scaring me. We did use a condom and he did pull out but I can’t help but worry. Is this normal? Also, my period is usually irregular (every 40 days more or less).. and it was due last week, and still haven’t come.. this is normal but I’m extra worried being that I had sex.

Need opinions on the tummy pains and nausea.. what’s wrong with me?