Measuring small, worried, having flashbacks

Yesterday I went in for my first ultrasound. I am 8w3d according to lmp. Embryo measured at 5w6d. Yolk sac was visible but no heartbeat detected. Dr said it is too small to tell whether or not the heart is beating. She has not diagnosed me with miscarriage yet, but she is very concerned. They drew blood and have me coming in for another ultrasound next Tuesday.

I have had one previous pregnancy, and it ended in miscarriage at almost 7 weeks. That one was also measuring a bit small. I miscarried naturally. That was last July. I have not had any spotting with this pregnancy, and occasionally I have some cramping, but nothing major. But I feel like I am waiting for it, checking every time I go to the bathroom, etc.

I am a wreck. I have lost hope for this pregnancy because it feels like it's all just happening again. I am having major flashbacks to the miscarriage and just crying all the time. My husband says he is concerned but hopeful, but I am not optimistic at all. I got the bfp on July 1st, 4 weeks ago, which seems early (to me) to get a positive if the baby is only just 6 weeks now. I guess it is possible but it doesn't feel right. I feel so stupid now thinking that this appt I would see a healthy baby with a beating heart and all my anxiety could settle down. I feel so naive for allowing myself to fall in love with the baby again.