I have a 61/2 month old that is weighing 110
You shouldn't worry. If you can clearly see his ribs, feed more food. If you have a hard time feeling his ribs, cut back. You should be able feel them with relative ease, but not see them. He is still very much a puppy and will be lanky until he finishes growing and filling out at 3 years.
my boy weighs 75lbs.... he gained 25lbs in 1 month!!!!!!!!!!!