PLEASE HELP ME!!

So I'm 15, and yes I know I'm "young" but me and my boyfriend have been together for 2 years and we've known each other for more then half of our lives. And well we started getting sexually active on September 10th, that was our first time. And we've always used condoms and he'd check regularly during us having sex. And my period came like 1 ½ week after that and now its October and my period was supposed to come yesterday but I literally don't and havent been feeling any of the symptoms that I always get before my period and its late by a day and maybe I'm just anxious but what do I do?