Hi, I am a week late with my period. I have taken tests and they all say negative. I am never more than 2 or 3 days late and I have no more stress now than I have had before. I feel pregnant, I'm nauseous most of the day, certain smells are revolting (smells I have always loved), I'm having mood swings a lot and I am more irritable than normal. I never have any PMS symptoms. I was just wondering if my HCG levels could be lower than normal women. Is it possible I could be pregnant or what else could it be?