6 days late, neg. Pregnancy test

Kelsey • TTC baby #1 ?????
I am feeling very doubtful lately that I will be pregnant this month. But my AF however is 6 days late and not sure why... I feel nauseous and fatigued and very tender breasts lately. But my pregnancy test came back negative. What do I do? When do I test again? I'm going to the doctors on friday..