Measuring a week behind

Hi all, I’m 7 weeks 2 days today and just had an early ultrasound, but I’m only measuring at 6 weeks 1 day with a fetal heart rate of 107. I have a very regular 28 day cycle, did ovulation testing, and got a positive pregnancy test at 10dpo (and also my husband and I only had sex 3x this month around ovulation due to work travel), so I just can’t see that this is good. I have another scan in a week, but was hoping people have similar experiences (good or bad) to share? I just miscarried in October, so I’m just so sad and worried. Thanks so much.