I have a 17 week old female Bernese Mountain dog i have had since she was 13 weeks. When i first got her she weighed 21 lbs. Now at 17 weeks she only weights 22 lbs. I have been feeding her 2 cups (Suggested by vet) a day of Purina pro plan puppy food along with lots of treats. She is very active, happy, and plays non stop with my Lab. Her legs have gotten longer but that seems to be about it. Should i be concerned about her weight? Should i feed her more or get a higher calorie adult dog food? I can't find much around about a Bernese weighting so little at her age.