I think it's highly unlikely that you could be that far along and get a negative BT but still be pregnant.

In the early stages it is definately possible but not later on. If you were only newly pregnant you would not be getting all those symptoms.

Even at 4 w 1 d my HCG was in the 400's and you only need 25 to be considered pregnant. By the stage you would be at now I was something like 75,000. There's no way a blood test wouldn't detect that kind of number.

I guess anything is possible, but I just think it's pretty unlikely.

Some women get "pregnancy symptoms" when they are not pregnant. I know I did a couple of times on unsuccessful cycles (but never missed a period). The ones where I conceived I didn't get any traditional early pregnancy symptoms until after I got a + HPT & + BT.