2 weeks late, on pill, pregnancy symptoms

I am 2 1/2 weeks late and have had pregnancy symptoms. I have felt on the verge of vomiting for the past 2 weeks and i have always had a flat stomach but i have recently noticed a "pooch" below my belly button, which i can't have any tight clothes touching or no one can touch my stomach without it feeling like an enormouse pressure that makes me want to vomit. Also, i have had a heightened sense of smell and wierd cravings, both of which people i work with have commented on lately. And i have been the most tired and moody than i have ever been, i cry for no reason! I went last week with my husband to get a blood test and it was negative. I am also on the pill, which doesn't mean a lot because my mom got pregnant on the pill. can i be pregnant or can it be something else? i would say i was accept for the neg results. Also, how long can a pregnancy test be neg for, like can you be 12 weeks and still have neg results, i know it might be improbable but is it impossible?