We have a 4 month old OEM, she is around 30 lbs and is eating 4 cups of food a day, spread over 3 feedings. Her stool is quite soft, and our vet swears that there is a direct correlation between amount of food served and stool consistency. So we are cutting her back to 3 cups of food a day and will see how it goes. She is on a really great kibble, so we are not really worried about her getting all the nutrients etc.
I think we are very prone to worry about underfeeding our Sam, every vet visit the one burning question we have is whether she looks too thin. So far tho our vet has tried to keep us calm and says she looks fine. We feed her after walking her for 10-20 mins, depending on the time of day and how much time we have. She does wolf the food, but then has a nap, so I don't believe she is going without. But who knows, kinda like babies, they can't tell you what they need. But she is steadily gaining weight and you can feel the meat on her bones so we will stick to the current diet plan and see what kind of improvement we can make on the stool consistency, since it is no fun to try and pick up the loose poops