late period please help

(I'm 15, I know please don't lecture) I had unprotected sex a week before my period was due 1 dec (my period is also a bit irregular) my SO told me he 100% pulled out before he ejaculated. My period is now 12 days late. I'm on cycle day 50 and usually they're between 30-35. Well my last periods have. I've been experiencing menstruation cramps a lot quite bad and sort of sick after eating. I don't want to be pregnant omg please don't lecture I know I get it