We have always fed a large breed puppy food to ours for the first year. Just like a real baby puppies need extra nutrients during their first year.
It is personal preference on what to feed, how much, etc. Everyone on here feeds a little differently, different foods, styles, etc. If your dog is doingell on what you are using and has a good coat, is active and healthy then he should be fine but if the vet has recommended a puppy food for him I would find a good one and mix it with the food you are now using until he is just on the puppy food until he is at least a year.