HCG help please

Alyssa
Hi all,
I had some very light spotting three days ago at 5+5, had an abdominal and transvaginal ultrasound as well as HCG bloods done. The doctor said my ultrasound was dating me correctly, no heartbeat yet though and HCG was 9051 and to retest in two days. At 6+1 my HCG was 10922 - only 20% higher. I've booked an appointment with my doctor, but I'm wondering if anyone can relate or had a similar experience? I'm so sure now that I am going to miscarriage as the doctor said my level should be 15000 by now.
Anyone who would give some insight, it would be super appreciated.
Thanks