Negative HPT 10 days post ET

I am 10 days post embryo transfer. They transferred 2 A Grade embryos. I had major cramping on Monday (5 days after ET) and thought it might be implantation but I can't be sure.  I took a HPT first thing this morning and it came negative. I am supposed to get a blood test done in two days time, is it possible to have negative result now but still be pregnant? I don't know if I should feel any symptoms at this point. I get some cramps but I think they are from the progesterone suppositories, my breast are feeling little heavy and big, and I get dizzy once in a while but that is all. Do you think I could still be pregnant?