Wrong date or possible miscarriage?

Candra
I went to the dr yesterday due to light bleeding all weekend and had bloodwork done and a transvaginal ultrasound. My urine test showed positive still, but there was not even a sac on the ultrasound. I go back tomorrow for another round of bloodwork. Has anyone experienced positive tests and negative bloodwork or positive both and a sac/baby show maybe 1 week later on an ultrasound?