The Nutriment recommendation for puppies is 4 - 6% of bodyweight daily. At 20 weeks Blue weighs 10.1kg and I currently feed him 450 - 500g Nutriment daily. I don't give him many treats, just a few very small pieces of sausage for training, and a Chewdles biscuit at bedtime. He has a raw meaty bone to chew on, which lasts him a week.
If you are concerned, you can always phone or email Nutriment, I have found them very helpful.