I missed my period last month and still haven't gotten it for this month. I've never been completely regular with my periods, but I've never missed one. I started having sex on a normal basis, and I had gone off of the pill in December. I took an at home pregnancy test, and one at the doctors and both came back negative. Should I take another one? Should I be as terrified as I am? I feel crampy like my body wants to start my period, but it hasn't come...