Am I pregnant or is my period late due to stress?

[Fafi79]

Hi, I am a 19 year old college girl who is having a few concerns! I had sex on Dec 1st with my boyfriend with a condom on. He pulled out and ejaculated in the condom but in the process he pulled the condom off to ejaculate on my face (sorry for the details). Instead he got *** near my vagina and all over my butt cheek. I heard it's nearly impossible to get pregnant from that so I wasn't too worried. But I am supposed to be getting my period today (the 27) or around now but I only feel cramps and no blood. I have no pregnancy symptoms at all and two negative pregnancy tests (the one that's supposed to detect it 6 days earlier). I don't know if I should wait longer and retest or go to a doctor for a blood test. I am not allowed to tell my parents because they would disown me. Maybe I am being paranoid but I can't sleep or think about anything else but this! Please give me your opinion! Thanks!