I'm 18 and I've been for birth control for 3 years. I was just about to switch from the pill to the shot because I take it at the wrong time a lot and I am sexually active. Sometimes I miss a day and take it the next morning. I'm on the third week on my birth control and i started cramps like I'm on my period and light bleeding. I usually start a new pack right away so im almost never having my period. This is very strange, is there any possibility that I'm pregnant?