pregnancy scare

So my bf and I decided to have unprotected sex but a few days before my birth control ran out and I missed a day. I started spotting a little but didn't think anything of it except that it was early. We had sex and it started getting heavier. I took plan b because he was worried within 72 hours and my period started to slowly stop. My period is late now and I'm not sure if it means I'm pregnant. Please help!