My period was supposed to have started yesterday and i still havent had it yet. (my periods are regular.) i took a pregacy test it was negitive. But i wanted to know if it could be wrong because i have been really tired, moody, crampy,my back and head both hurt and feeling like i am going to throw up all day. i went to the doc office to get my next cycle of birthcontrol and the nurses said i may be but i wouldnt know till i took a test.So again is there a possiblity that i may be pregant?