what do i do

my fiance comes home from work in 6 days. we have been ttc for 13 months. i am currently 6 days late but i cant see lines on any tests. should i wait til he gets back to test again? We had sex feb 13th, the day before he left. and then i went to visit him march 2nd and we had sex again. but i dont know why im getting negative tests at 6 days late.