The recommended amounts on food bags are no substitute for how your pup looks, in my opinion. If they're not skinny, dull or lethargic, they're probably eating enough. Trust your instincts
Also, I've learned that it's not always the size of kibbles that pups can dislike, it's the texture and density too. Edie won't eat dense, dark kibble like Orijen or Fish4Dogs, only lighter biscuits like Burns or Royal Canin. Smashing or soaking them didn't work.