could I be pregnant?

I've been on the pill since last May and I got my last period on December 27. For the last couple of months I got my period on Tuesday when I was supposed to and before my period became regular from the pill it would always come early. It's never been late. I got my period today, 2 days late and it seems to be over already. I took a couple of pills around 5-6 hours late and there was one day that I had to double up. This is the first time I've ever done that. Along with being on bc, we use a condom and my boyfriend pulls out every time. Is there any chance that I'm pregnant? Or is it most likely because of taking my pill at weird times? I'm going to test tomorrow just to make sure, but what is the chance that I'm pregnant? I'm almost 18 and cannot have a baby right now. I've also been having slight cramps since Monday and I shed two pieces of uterine lining today which I've never done before.