2 weeks off?

My lmp was august 1st. Last night I went to the hospital for bleeding and cramping after all the blood tests and ultrasound they told me that I was only 6w2d but I should have been 8w. My hcg level was 17000 and the baby's heart rate was 90bpm. Today I followed up with the ob they also did an ultrasound. The baby's hr was 111bpm and I was measuring at 6w3d. They say the baby is fine for now..but I'm still bleeding and it's red but only when I wipe (tmi sorry). So it's a little scary. Has anyone else have had an early ultrasound that showed that much of a differance? I had to go for dehydration almost 2 weeks ago and they did an ultrasound and I was measuring 6w then with a hr of 80bpm I'm so confused. Help