So confused!

So I was 5 days late on my period, then after having sex I started bleeding and then next day I started my period. I lasted like 5 1/2 days. I started to B.C pills and felt sick and my period will stop for a while. I stopped taking b.c pills on the second day, so I only took it twice. Then on the fourth day of my cycle, I had sex because I thought I was done but I wasn't. Today, where I have no period I wiped and there was brown blood. But I'm not spotting. Then all of sudden I felt sick but didn't throw up. I don't wanna take a p.t just because I don't wanna let be down. In your OPINION can I be pregnant or could it be just cause I took b.c pills for two days?