He looks very young to me, so hopefully your Vet can be helpful with determining his age.
Most puppies sleep about 22 hours out of 24. It's the other 2 hours of mayhem and housetraining that keep us on our toes. Very young pups will eat, play for a bit, and sleep. That is normal. They become "busier" around 10 to 12 weeks of age, and often appear to have set backs in house training, when in fact, it's just that the humans haven't caught up to the pup's new schedule.
Young pups have no ability or concept of bladder or bowel control. While it's fantastic that he is already doing everything outside where he should, continue to praise, praise, praise that behaviour and if he has an accident, remember it is YOUR fault. Clean it up quietly and without any fuss.
Please post tomorrow after your Vet visit. We will all be interested to hear what the Vet has to say.