where are you, period!?!

ashley
so i had sex with my boyfriend last sunday, unprotected, (not on birth control), and he came inside.. i know, it was stupid of me, but it just kind of happened. i was supposed to get my period 4 days ago, and i still don't have it. for the next few days after sex, my boobs were so sore I literally had to wear a bra at all times. (and no, he wasnt rough)
 
HOWEVER.. in january, my cycle changed. my period was 16 days late (but i hadnt had sex, so i knew I wasn't pregnant), and it hasn't been regular since. and sore boobs is a new period symptom i get, that i never had before.. so i was kind of attributing it to that. 
not having my period is scaring me though!! has any of this happened to anyone else!?!?! help!