scared about being pregnant

I've been on my birth control for a while now and for the past 6 months i've spotted continuously (probably because I don't take the placebo pills). I've been having unprotected sex and now all of the sudden I've stopped bleeding...! Could I be pregnant? I've taken my birth control religiously but am often off by an hour a lot of days. If I stopped bleeding because of pregnancy, should a pregnancy test come out positive or is it too early? help!