Going to miscarry

Went to the doctor yesterday at 9 weeks 4 days. Ultrasound showed a sac and couldn't find heartbeat. She said I may have my dates wrong so it could still be too early to see anything but I'm 100% positive my dates are correct. She's having me come back in a week to see if things progress but she said she's not very optimistic and chances are not likely. I'm so heart broken. I'm praying things turn out to be okay. But I'm preparing myself for a loss. I'm so sad and emotional, my man is being awsome and so sweet to me but I can tell he is hurting too. It feels like I've done something wrong and am letting him down bc I couldn't keep our baby healthy. 😔