I've always had problems with my period, even on the pill

Okay, here's a doozy for you. Im on birth control, have been for years. I very rarely tale my pill at the same time every day, but every day without fail. I've always had problems with my period, even on the pill. I skipped my last period by just starting a new pack of active pills instead of letting my period come. Should be on my period now, but I got nothing but a bit of brownish stuff that one usually gets at beginning and end. I didnt miss any pills at all and got nasty cramps and bloating, but no blood. What do you think?