Somethings Not adding up right to me!!!?

the situation is just driving me bonkers trying to add it up ! At 9 weeks I went in for an ultra sound and I was told there was no longer a heartbeat and baby stopped growing at 6weeks 4days.. I dont see how that could be when at 7 weeks I went to the hospital and they saw my baby and the heartbeat! I had also had one done at 5weeks 3 days && that was my first ultrasound at hospital.. second ultra sound they said my baby had grown since last time and they actually saw a heartbeat.. So if my baby stopped growing at 6 weeks 4days. How did the hospital see the baby growing and a heartbeat at 7 weeks?? It makes no sense to me, my first 2 done at hospital took at least 40mins but the one i had where they told me baby stopped growing only took no lie at least 5mins if that??? it was done a a clinic where they are suppose to be top notch! I would think it would take longer then 5mins just like my first 2 took at least 40mins!! Im very confused and upset.. My hormone levels yesterday were a good high im having them tested again tomorrow. just none of this makes sense esp the ultra sounds.. && all 3 were done were vaginal ultra sounds..