I'm concerned!

My period used to be super severe and the cramps used to be so bad that I threw up, but once I got on birth control that worked for me I wasn't throwing up and it was slightly less severe. After being on the same pill for around 6 months this current period has been super strange. It is so light it's barely there even though I still have cramps to deal with. I'm not sure if I'm pregnant even though that could be a possiblity, I'm just unsure of what to do.