Could I be pregnant?

Hubby and I are trying to conceive, this would be our second baby :) ... Today I am 6 days late, first pregnancy test I did was at 4 days and that was negative and another yesterday at 5 days since I just felt pregnant, that too was negative. From time to time I feel a little nauseous.. Should I just try another pregnancy test in a few days since my hcg level might be too low??