ok so im 16 me and my boyfriend have always had unprotected sex except with withdrawl. Lately i have been feeling like vomiting, ive been having some bad cramps every now and them, my back has been bothering me, ive been urinating more, and non stop eattin, but i had my period on the 26 instead of today when i would normally start and it usually last 5 or 6 days it only lasted 3 so i took a home pregnancy test but it was negative and i have been feeling this way for a week now so can i possibly be pregnant?? even though the test was negative