Babies at this age should be drinking 16 to 24 ounces of breast milk or formula a day. If your son doesnt like milk but takes adequate dairy products, he should be OK. Instead of plain milk try varieties of milk like almond milk, soy milk, whole fat milk etc. You can try making smoothies as well with banana, strawberry etc. But don't forget to serve extra protein in the form of chicken, fish, beans, or eggs.
At his age, you can introduce variety of finger foods for him like toast fingers, fruits and precooked veggies etc. Babies readily eat cereal, cooked noodles, soft breads, and rice. Over the next three months your baby's diet will begin to resemble that of the rest of the families, with 3 meals and 2 snacks each day. You can also give 4-6 ounces of diluted 100% fruit juice in a cup.