9mo is feeding ~24 oz of formula now & has never gone beyond 32 oz. consulted ped multiple times and said vit d are not necessary. no teeth yet. ?

Does not need it..: Premature infants, exclusively breast-fed infants, dark-skinned children on vegetarian/vegan diets, and children with malabsorption are at risk for vit D deficiency. Human milk typically contains a vitamin D concentration of 25 IU per liter or less. Therefore, a supplement of 400 IU per day of vitamin D is recommended for all breastfed infants. Not necessary if giving vitamin-D fortified formula

Feeding: 24 ounces of formula is about right for this age. Is he eating baby foods or table foods as well? He should be getting the Vitamin D in the formula. Is he gaining weight well- that's the most helpful way to know if he's getting what he needs. It's common for children not to have teeth yet- the average time for the first one is between 6-9 months, but they can certainly be a bit later.