Ok so my boyfriend and I had sex about a week ago and I have had cramps and nausea and headaches with very little spoting and I'm on the pill and I had these cramps before my period and they got worse the day after my period ended and have not stopped. My cervix is low and closed, could I be pregnant?

The spotting of course could be sign of pregnancy. But at one week, normally you will not have any other signs at all. The first real sign you will ever see would be missing your next period.