A.M.
This website has a lot of great information about home pregnancy tests:
http://www.peeonastick.com/
I personally don't get a positive pregnancy test until AFTER my period is due -- happened with both pregnancies. So I would wait a week and then test again. With my second I already KNEW I was pregnant, but the test said negative. I didn't believe it (I'd been there before) and sure enough, a week later it was positive!
Good luck!