How much to feed a puppy?

[snorzzz]

It seems like he is always hungry.
I feed him 3 times a day, 1/2 to 3/4 cup dry per feeding.
Black lab, 8-9 weeks old, about 15-20 lbs.
Lots of snacks and treats between meals.

He has been wormed and is healthy looking, not skinny.
But it seems like he is always hungry, so I'm concerned I might not be feeding him enough at meal time.

Any advice?

Thanks!