Need help!

Me and my SO had unprotected sex the day before yesterday (may 8th), and he told me he did not ejaculate in me but that (because I was on top), he was worried about pre-cum... I was not worried at first but now I'm unsure. My period is supposed to come in 6 days from now (may 10th) but I never had a regular period in the first place. My main concern is • if my period is already irregular what else can I look out for before taking a test?