My son already 7 months old, he just drink 4-5 oz milk per meal, don't worry.
When my son was 2 months old, he doesn't like milk, he drink 3 oz per meal, less your baby. I am not happy also, I hope when he can eat congee, mabey he like it, but he donesn't like also, now I don't force him to eat and drink, let it be. as happy as he is.