It really hurts after knowing about your child, but I am very sorry to say you that most of the brain( about 90%) grows by 2 years of age. So if the child is now of mental age
of 6 months there is very little chance of much improvement.
Consult a pediatric neurologist
, ophthalmologist, E.N.T. specialist and physiotherapist as now the aim should be to achieve maximum physical and mental strength by rehabilitation