I've been on birth control since the birth of my son almost two years ago and have always had a heavy 6 day long period. This month I have been nauseous, sensitive to smells, and having cravings, making me feel as if I must be pregnant, my period 2 weeks ago was only 24 hours long but I took a pregnancy test just after that and a week later and both came up negative, any ideas? Pregnant or not?