HCG didn’t double..

My husband and I have been trying to get pregnant since October 2021. I had a miscarriage this past May, then unexpectedly found out I was pregnant again on July 26! I calculated I was about 5w5d. I went in for HCG test the next morning and was at 757. I got a repeat test today at 6w and it only increased to 968. I am so worried it will be another miscarriage. The wait until Monday to call my OB about next steps is brutal. Anyone ever have a similar experience?