I think your dr's are doing a good job. When my son was born, he was in the 95% and when we was weaned at 17 mths old...he was in the 5%. and now he's 20 mths old...and as far as we know he still hasn't gained or lost anything.
He was having diarrhea-like stools. But I was figuring it was just because he was breastfed. but they should have firmed up when he started solid foods more...but they really didn't. But the thing that concerned my doctor for Danny was because of his slow downward trend on his weight scale percentage. That can mean that there's something wrong going on in their system.
Our doctor also ordered blood work for him...and stool samples. They checked for possible allergies and Celiac. I requested Celiac testing based on what I read online and how it can affect their digestive systems. It seemed to fit for him. A couple tests I got back are: IgA deficient and IgG came back saying possible Celiac. This Wednesday he does to see a GI doctor for more testing.
I'm curious what you mean by no major spit up or diarrhea. If you notice any spit up or any soft messy like stools they are worth speaking about to your doctor. Especially since your baby is not on breastmilk and also eating any solid foods. It's possible your little one may be sensitive or allergic to milk. In the blood tests they can tell if your little one has sensitivities or allergic to different foods...including diary. I was told my little one is at least sensitive to milk.