Don't have hope...

My first ultrasound I measured a week behind and was 5 weeks. They saw the yolk sac but no baby yet. I had a follow up ultrasound on the 28th and was 6 weeks. I saw baby and a heartbeat, but the heartbeat was only 64 which is really bad. I have another ultrasound on Friday but I am expecting the worst. I don't have any miscarriage symptoms and my HCG is going up but I'm worried that it will be a missed miscarriage. I am so worried and sad. I feel hopeless. I'm trying to find success stories with this low of heartrate but can't find anything. I just don't know what to do.