Possibility of Pregnancy Without Sex

Patient: I’m 16 years old and I have a boyfriend. We mess around a lot, and the other night I was in my underwear when he ejaculated. I haven’t gotten my period, but it has been pretty irregular over the past 6 months (I’ve only gotten one period in 6 months). It’s only about 5 days late and I did do a lot of travel recently, so there could be other factors. Is there any chance that the sperm could’ve gotten through my underwear and into me?

Symptoms: Late period (5 days, already was irregular)