No heart beat at 5 weeks 6 days

Just curious to know your thoughts. I had an ultrasound last Monday and I was roughly only 5 weeks and 6 days along but again that’s just a guess I’ve attached the photo below. My concern is should I there be a heartbeat at this stage? The hospital report came back none viable pregnancy…….. my family doctor is confused by this as I’m to “early” and everything looked good in the ultrasound. I’ve had on and off bleeding but my HCG is still going up and haven’t had any bleeding since Monday. Does anyone have an experience with this? Thank you.