Could I be pregnant still?

My husband and I have been trying for a couple of months to conceive. I have been watching my ovulation calendars closely. My periods usually come every 26 days like clockwork. It has been this way for almost 2 years now. (I haven't been on any birth control for 6 years). This past month I was five days late. I woke up this morning with cramps and bleeding. (It doesn't feel like a period) I usually have no cramps. I have taken home pregnancy tests they come back negative, I went to the Dr. and he gave me a blood test and it came back negative. (I was only one day late at this point) But he said for me to come back in 2 weeks, if my symptoms dont go away as it could just be too early to tell. I have been nautious for 2 weeks now with vomitting. I am peeing almost every 45min to 1 hour, I feel light headed and dizzy. Is it possible that I am pregnant still? The bleeding is light, with light p-ish turning to brown.... but it is definately there. Is it possible that I could be pregnant?