S.M.
Hi, B.. Well, there are drinks that give the child a transition from formula to stuff that is a little closer to milk, but are not plain milk. It's been a long time since my child was that age, so I forgot what it's called, but it's something like "stages" or "first steps."
Plain cow's milk at too young an age may be a factor in Type I diabetes in very young children, so that may be why ppl have told you not to feed your son plain milk.
Unless he has a weight problem, formula will not hurt him. It has more calories than plain milk, so if you need to watch his weight, then you will want to feed him something else, but otherwise, formula will not hurt him. You could try soy-based or rice-based drinks for children, but at his age, he should be eating solid foods and will not need to take most of his protein and vitamins from milk or formula the way a baby has to.
Peace,
Syl