What should i do

I had sex on 1/30/2k15 and I was ovulating n had ovulation ovulation bleeding for the first time. Well we didn't use a condom but he pulled, I took a dollar pregnancy test but I believe it was negative cause I only saw 1line. But I haven't had my period since mid-January so what should I do? I'm kinda on the big side so idk if that has to do with it.