On the pill; Pregnancy?

don't take the pill at a regular time; anywhere from 9 to about 1130. About a month ago, my boyfriend and I have stopped using condoms. About two or three weeks after we stopped using condom, I started spotting. (Spotting began Saturday, May 2nd). It keeps going, every day, but it's very light, and always dark brown or very light red. I've been getting horrible cramps with it, which the nurse who gave me the pill promised would stop, because that was why I went on in the first place. Also, I've been very bloated and constipated, but when I get bad constipated, it'll be like suddenly I have to go NOW when it happens. Sorry for the gory details; what do you think this could be?