for puppies you can generally go by the guidelines on the back of the food bag. Since your pup likes to eat alot i'd stop free feeding him. my pup used to eat 1/4 - 1/2 cup of food a day. So since he's 13 weeks, split 1/2 cup of food into three meals and feed him a breakfast, lunch, and dinner instead of a smörgåsbord of food all day long.
