I need some reassurance girls

So basically, I’m a virgin for background my boyfriend fingered me properly a few days ago, we were like 12 days after my ovulation and I think it’s virtually impossible that I would get pregnant because me and him both think his hands were clean (no semen) but for some reason my period is late by 5 days (I have had cramps and diarrhea like usual) and I have pretty consistent periods getting it on the same day for the past months, I really don’t want to buy a pregnancy test if I don’t need one