Unprotected sex day before period and I haven't started my period...

I had been taking birth control religiously for two months, I stopped while I went through a moving  process so I was off it for about a month. So I got back on it BUT I only took it for two days before I lost my virginity (technically unprotected). This was A day before my period was supposed to start. It hasn't started... I have been regular 18-20 day cycle ever since the age of 12 and now I've skipped a whole entire period (5 days). I know it could be me just confusing my body but I'm not sure. I can't take a test yet because I have to wait two weeks after sex before I can... I'm just impatient. Any thoughts???