Could I be 5 wks pregnant?

I had unprotected sex a day before and day of my ovulation last month. I am now 6 days late for my period. I took a pregnancy test 3 days after my missed period in the middle of the day and got a negative. I've been cramping on and off for a week, and my nipples have been sore on and off. My stomach has been feeling a little yucky but I haven't been throwing up. Should I test again? And could I still be pregnant if I get a negative result?