What Causes Vaginal Spotting And Cramps While On Birth Control Pills?

I am 16. I have been taking the pill for a week and a half usually taking it between 9pm and 11pm. I had sex 6 days ago and again 3 days ago. 2 days ago I had some light spotting and cramps, and I've had these cramps ever since then. I also keep feeling like I need to pee but when I go there is nothing. What could this be? Is it pregnancy? I'm so scared and I've convinced myself I'm pregnant. But my mother and boyfriend think I'm being ridiculous.