I had sex while I was on my period then a week later I felt pregnancy symptoms, its been 4 weeksz since my last period and I thought I was pregnant but today I got my period its been way lighter then other times and its really dark also. Can I still be pregnant??

If you got your period, it's unlikely that you're pregnant. Could you be? Sure. It does happen. If you're worried, then try a pregnancy test using first morning urine.