Could I be pregnant?

I had my period starting April 27th, and had unprotected sex on May 13th. I was cranky a week afterwards, followed by a couple days of having a loose stomach. What I believe to have been my period started May 26th. My period is usually heave for three days and then mild the last two. However, this period was heavy one day, light the next, and nearly nonexistent the third, then gone. I've been feeling bloated, (which I have blamed on being slightly constipated). I may be making myself crazy over nothing, but I do not feel right about that weird period preceded by the cramping. Help?