Sorry for the delay in answering. I was on a family vacation. There was no internet access which was very unsettling.
You are on the right track with your son. You seem to be keeping a good eye on his diet. I would add organic whole milk cheese if he will eat it. Calcium is very important for growth, development, learning and of course strong heatlhy teeth and bones. I would be tempted to add a calicium supplement if he doesn't eat a sufficient amount of Calcium rich foods on a regular basis. You can also try a variey of other foods that are good sources of Calcium.
I am not a fan of supplements for a child either but proper Calcium intake is very important to his growth and development. Try adding other foods first and see how it goes.
Thank you for the question. Sorry again for the delay.