passing out??

hello. i am supposed to start my period today but i havent but that is not what i am worried about. i took a pregnancy test 3 days before my expected period in the late afternoon and it said no. i know its best to take in the morning so i am thinking that this test might be wrong. because i have felt nauseous, tired, moody, and having to pee a lot esp at night and my allergy symptoms are worse than usually. last night i felt soo nauseous and i kept having hot flashes and today at work i felt like i was going to pass out because i had not eaten in a few hours and i was exhausted…are these signs of pregnancy or am i being paranoid??