OB-GYN says I will miscarry

- 29/08/16 - 379 

- 31/08/16 - 814

- 09/09/16 - 44000 (didn't give exact)

- 12/09/16 - 45647 (today)

I had my first scan on the 09/09/16 before we got HCG level back and we saw the sac and the yolk but no fetal pole or heartbeat.

OB-GYN is scanning me again tomorrow but has already started acting as though all hope is lost. I haven't bled or had any cramps, symptoms still present and I'm still hopeful. 

Is it possible that because tests were only 63 hours apart and not 72-96 that this is why they're low. And maybe that 6 weeks is too early to see a heartbeat sometimes, everyone is different right??

Anyone have any success stories and/or stories of professionals getting it wrong??