Take a home pregnancy test....cheap and quick answer. Yes, if you mess up your pills and then not take them, continue to be sexually active, and haven't seen a period in 5 weeks....it would be VERY possible that you could be pregnant. It doesn't mean that you ARE, just very possible.
I agree, you need to poas and find out for sure.
Out of curiousity, what made you forget your pill 4 days in a row?