If you ask me, going by what my lo one eats, your ds is eating plenty. In total my lo takes maybe three oz. of solids in the whole day, with maybe 20 oz of formula. Every baby is different, and I'd say if you ds is active, contended, and happy, then hes getting enough. As for night wakings, how are his naps? How long does he nap for, how many times a day? Does he sleep independently for his naps? Even though the night wakings are random (suggesting he's hungry), but if you're offering him things to eat and milk, and he doesn't take any, unfortunately there's nothing you can do, except ride it out.
Sorry I wasn't much help.
Sumita