6 week scan, gestational sac, yolk sac and fetal pole but no heartbeat!?

I went for an early scan today just out of being impatient and I'm a worrier anyway. Completely regret it. We went in for the scan and the sonographer couldn't see much on the abdominal scan so had to have an internal scan. She scanned away for what seemed like forever, only to tell me there's no heartbeat. She's suggested a re-scan next week. I've read loads of things online about it being normal to not see one at this stage (I am only 6 weeks +1) but I'm still panicking. Any success stories after seeing gestational+yolk sac and fetal pole but not heartbeat?