Here's the story:

Had my period in jan. I think around the 16th.... I usually start the next month 1 or 2 days ahead of that (so I was assuming the 14th in feb.) Well, it's now the 20th and I haven't started yet, but I've had some symptoms.... I had sex a couple times around the 3rd. Today I took a pregnancy test and it came out negative, but I'm not convinced either way..... help?!?! Any thoughts???