Pregnant r not please help me out?stressed?

I missed my period for almost 2wks now...I took a test the day of& it was negative!I have been really hungry and very sleepy...when I stand for along time I get dizzy and in the morning I feel like throwin up but can't and and my lower back has been aching..it felt like my stomach is tightening sumtims!I be really thirsty but wen I drink it it makes me wnt 2 throw up!I am constipated...I was thinkin of taken another test r should I go to the doctor!please help is it a possibility