Im So Confused Help... Missing a Pill Not Gettin My Period

So I have been on birth control for 4 months now and I have been pretty good at taking it I have probably missed one pill here and there but I have always just taken two the next day. I stop taking the pill on sunday and then I usually have my period on wed of that week, this last satuday I kind of had I sex I guess... My guy went in like for a sec but I don't think completely and then he pulled out, the thing is I missed my pill (it was the last one) and I just took it the next morning ( usually take it at night) but now it is thursday and I haven't had my period, I have like cramps but no period, I am really worried what should I do, im willing for any advice... I am just hopeing my period comes.