Another pregnancy question....

I've been on the pill for about 5 months now. I've never missed a day and I take It regularly at the same time. (8am) my boyfriend was home from school a month ago and we had sex, however, it was 3 days before my period pills. I was spotting during a couple of those days when we had sex. We also didn't use a condom (yeah, yeah. I know. Stupid.) so, I'm wondering if us having sex before my period pills while spotting, increases my chance of pregnancy. I'm supposed t start my period again tomorrow but I don't have any spotting this time. Should I be concerned? And are you even SUPPOSED to have breakthrough bleeding before your period?