First HCG 71,669 second one didn't double it was 87,447

Griphen
My midwife just called and told me my levels didn't double. My first blood test was Thursday and it was 71,669 and blood test taken 48 hours later was only 87,447. I'm super worried cuz I just went through a blighted ovum miscarriage in November. We're scheduled for a vaginal sonogram tomorrow. I hope and pray we see a heartbeat! I'll be 7 weeks tomorrow.