Help!

My boyfriend and I finally decided after three years of dating to have sex. I was 3% fertile, five days until my period. We used a condom, no rips or tears and the condom had spermicide on it. As of now I am seven days late and I took two pregnancy tests, which said negative. I have been less active, due to being on school break and was wondering if this sort of thing happens to most people? I know sex changes your cycle and can delay it, but I’m still a little freaked out.