missed period?

So I was supposed to get my period on march 3rd and it's been 8 days. According to a pregnancy calculator I'm supposed to be 5 weeks pregnant and I conceived on Valentine's Day. Which would make sense bc I had sex that night but we used a condom and even pulled out. So I could be pregnant, but I feel no symptoms at all. I took a pregnancy test and it was negative. Is there a chance that I'm pregnant or am I just missing my period this month? I have skipped a period but that was probably in my first two years after getting my period. I've been late up to 11 days this past year.