I would ask your vet what he/she recommends.
I fed my Golden Retriever about 3 cups of food per day 2 cups in the am and 1 cup in the pm. ( I figured she would burn the extra during the day that is why the bigger portion was given during the day). I did that until she was about a year old (she is now 16 months old). She is on the lean side and weights about 47lbs, which is a perfect weight. She gets lots of exercise, which is also something to consider when trying to figure out how much to feed your puppy. Big dogs need a lot of food to help them grow properly. I think you might need to feed more, but ask your vet, they should know best.