No period after taking pill// pregnant??

I had sex on Saturday without a condom and he came inside me but straight after we went to the pharmacy and got a pill called postrelle-1. I took the pill on the same night and the doctor there said if I were to vomit within 2-3 hours I would have to retake the pill but thankfully I didn’t. He said if I don’t get my period within the next 5 days I should take a pregnancy test. And now I’m really scared and I still haven’t got my period and I’m too young to be pregnant. I don’t know what to do and I’m starting to stress bad. And I’m not fertile right now could I still get pregnant