I'm freaking out!!

So my boyfriend an I had sex the night before last and he came inside me. I think I should be fine because I've been on birth control for a while now but I had missed the day before and took double the dosage the day we had sex. I'm really hoping that I'm not pregnant, my period is supposed to come in a few days but I'm scared to wait and I don't know if I should just go take plan b just in case. I read up on it and it said that if I'm already regularly taking birth control it wouldn't be as effective.