6weeks 1day and no heartbeat- long road

Found out I was pregnant with a HCG of 10.6   2 days later  44. I had an eptopic in the spring so after some cramping I had a repeat HCG 7 days from the 10.6 and it was 657, 2 days later 1650! Numerous transvaginal ultrasounds, checking on development and everyhting was looking good. At 5 weeks 5 days one doctor thought she was seeing the flicker of the heartbeat, but could not get a sound becuase it was too small .23cm. At 8 weeks since my last period a transvag ultrasound showed the fetus was 6 weeks 1 day and measured .43cm which is accurate for the time frame, however this doctor did not see a heartbeat and told me that if we do not see one in the next ultrasound (3days away) we should schedule a DNC. This all seems a little premature. Can the fetus move at thus early stage is there a chance the heart is just too small and that the fetus moved and she can't detect it. 3 days of waiting and worry is killing me...... I thought I was having twins in the beginning with the high HCG numbers and now I will be happy to just see this one little heart BEAT!