I had sex a week before my period was due I got my period but it is vary light and not my normal period could I be pregnant.

You could possibly be pregnant, if it's a light pinky spotting or a light brown spotting it could be a sign of pregnancy, but it could also just be your body flushing out left over period or a sign that your period it about to start... Best thing to do is go get a pregnancy test because that's your only possible way of knowing. I've had pregnancy scares before and they aren't nice especially when you aren't ready for a child

Anytime there is penile insertion there is the risk of pregnancy. But the only way to determine if you are, is using a pregnancy test. Either a home test or one from your doctor.