Still negative!!

Took a pregnancy test and it was a big fat negative so I was expecting my period two days later. It's been 4 days and still no period. First day after my missed period I tested again and it was still negative. Tomorrow will be day 5 with no period in sight. I'm not sure if I should test again, but I don't want to be disappointed. I was almost certain I was pregnant, my boobs hurt, I've been nauseous. What is going on!?