Help me

Okay so this may be a dumb question and I’m sorry about it my sex Ed classes were barley even anything I don’t remember them but so I was grinding on my boyfriends dick 3 days before my period and I had thin thin leggings on and a thong that was barley covering my vagina and he didnt have any clothes on and a couple minutes while I was off his dick there was precum but idk if it was there while I was grinding on him so like could I be pregnant if precum went through my pants like it didn’t feel wet but I was already wet myself so I couldn’t tell and I’m a virgin and I’m just scared we did this 3 days before my period on a Sunday and then my period started on Wednesday but I heard that if you do anything sexual before you period that it can start but then not start the next month if your pregnant so someone please help me