What food are you feeding? The quality, calories, fat content etc is critical. 4 cups of cheap food may have less calories than 1/2 cup of quality.
I feed puppies 3x a day til they are 6 mos old, particularly smaller breeds. Until they hit about 20 pounds, it is harder for them to regulate blood sugar levels with 2x a day feeding. I know many who do feed only twice, but I just like to know they can utilize the food and can maintain stable blood levels. I won't bore you with research, but a good article in general:
http://www.vetmed.vt.edu/vth/sa/clin/cp_handouts/Nutrition_Growing_Puppy.pdf
All that said, if your pup is neither fat or thin, is healthy, then you are probably fine. If you see problems, evaluate. But you can never go wrong with top quality food. As for puppy or adult food… I switch at 6 mos over to adult. Many stay on puppy food til a year.