Hcg in blood not urine ??

Shell

Has anyone got negative test but a positive blood test. Two weeks late and no sign of af coming. Been testing negative, thought I got a faint line yesterday on a clear blue test but I think it was just my eyes. Dr ordered a blood test today and the results will be in tomorrow. Just wondering if anyone had anything like this happen. I have read a few things what some people never test positive on a home pregnancy test so I guess I am hoping that it true.