I Really Need Hell. College Student And I Don't Want

I really need hell. College student and i don't want to be pregnant. On August 21st,2015 i ended my period. On August 22nd,2015 i had sex. He did not use a condom for the first like 5-10 mins then i stopped him and told him to put it on (I know stupid). So i took plan B about 8 hours later because of pre-cum. So i had sex on Saturday. Got a period on Thursday, i guess from plan B. It's now October 13th and i have not had sex since. But i also have not bleed since the 29th of August from plan B. I am experiencing lower abdoman tightness and cramping. I have taken 4 pregnancy test since i missed my period in Septemeber. Could i be pregnant? I just started college and i'm stressing about this. Which i know can make you later on your period. I just need help, i plan on making a appointment with a doctor soon.