Is he too skinny?
Robin was born May31,2012 he eats a little more than three cups of puppy food a day.it is what the bag advices to feed my puppy I'm feeding him large breed nutro I also fed him a chicken breast(boiled on Tuesday and he just gobbled it up. Also since then he really doesn't want to eat the puppy food and went down from 3. Cups to 2 1/. Can it also be the heat? It's been pretty hot in la lately . He also drinks water like a camel. He has also been busy running around in the back and digging holes and dragging stuff to his bed. Heres a pic of him I get pretty worried when my pets don't wanna eat what they usually eat specially this 11 week old 

He is a cutie! He does not seem skinny at all in this pic. I can tell you that when you fed him the chicken...he is looking for more chicken, most likely cause of him not wanting his food. I'm sure others here will let you know more but I think the feeding of 3 cups per day is normal. He sounds like a very normal pup.
Chicken vs kibble...CHICKEN!
Hes fine deffintly eating enough. As long as his ribs arn't dramaticly showing when hes doing daily activities, I wouldnt worry.
A layer of fat over the ribs while still seeing a waist line is the way he should look as he grows.
He looks just as Harley did when he was his age.
I usually only use the guidelines as a base line. We're feeding TOTW atm and the bag says Harley should be getting 3 1/2 - 4 1/4 cups/day. During the cooler months he gets 6 1/2 cups and the warmer months is more like 5 cups.
The best way I can tell if I'm feeding he enough is how quickly he gobbles it up. If he wolfes it down and looks for more after, then the I'll up by 1/2 cup until he is satisfied. :)
What a cutie you have by the way :)
As a growing puppy there will be days at a time he almost looks to heavy and days he looks like he's starving as they hit a growth spurt.

Photo Gallery
RobinPet Profiles
Sorry about the grammatical errors I'm doing this through my phone. The puppy food advices me to feed him 3 cups a day