Late by 3 days

So I really havent had sex much, last time i had sex was on the dec 30th but only for like 30 seconds and we used protection. The condom didnt pop, i checked. My period has been late this month, last month and the month before that. Should i be worried? Im afraid really. Im 16 so im afraid to talk to my mom about it. Should i be having symptoms? Ive been feeling normal. I stress when my period is late by a couple days