It is very much based on the individual dogs - just like with humans!
Jazzy always has had a tendency to chubby-up, even as a puppy I had to be very careful about how much she was fed. She's {2 yrs old} currently on a low-fat dog food {which she likes as well as I like human low-fat food, LOL}.
Keoki, on the other hand, at 5 mos is lean. He is currently fed 1 3/4 cup of Puppy Chow a day {broken down as 3/4 cup in the morning, 1/2 cup around mid-day, and 1/2 cup in the evening}– which I think is about what you are feeding Myran, with multiple treats for training purposes throughout the day.
Sometimes I can just see the outline of his ribs, depending on how he is standing. They are always easy to feel.