First of all dont worry about your sons diet. He is fine and whether he gets a bit more milk or a bit more solid food is not a big deal.
Dont be afraid to try foods with him- Get a couple of jars of 3rd foods.. Try to feed him the 3rd foods. If he eats them- then he is ready- if he gags on the chunks - he is not ready- wait a week or two and try again.
3rd foods fruits and veggies do not have chunks - but the 3rd food dinners do have soft pieces like noodles or carrots.
Babies should get about 24 oz of formula until age 1- after age 1 they switch to whole milk and they shoudl get about 16 oz a day.
If your son can pick up gerber puffs- try cherios, my daughter started eating canned fruit cut into small pieces about this age. - try canned pears first- peaches are slippery.
Once he has the hand coordination-to pick up fruit pieces - try canned veggies. green beans, peas carrots.. you will be surprised with what he will eat if you offer it.
Babies move quickly through the baby food and on to table food.