Sex and maybe a pregnancy ?


Okay so I’ve come on here because I need guidance, I am 17 years old and well, I still a virgin, kinda at least, me and this guy did sexual things and he put the head of his penis inside my vagina, and we don’t know if there was any pre cum, anyways that happened around 2-3 weeks ago. Fast forward I was very nauseous for a good 3 days but then it passed, and my period was supposed to come today and it hasn’t came, what do I do? I honestly feel so scared and I can’t talk to my mom about it cause she’s super against sex before marriage, I’m terrified.