Hello. Me and my girlfriend were dry humping with our clothes on(4 layers) and in the process, I ejaculated but I'm very sure that it was in my underwear itself. She got her periods on the 6th of may and hasn't yet got her periods. We are worried.

Could this be pregnancy? She had some stress and this added to this, this issue increased her stress and tension. We're worried and would want to know what the problem could be because pregnancy is not something that either of us are ready for and we're young. I'd like to add that she's not finding any changes in her body either(that could indicate pregnancy - nausea, frequent urination, fatigue etc). And today being 17th, it is almost 9 days since her period was to come but it hasn't. We're worried and would like to know all the possibilities.
Thanks in advance.