How little milk is too little?

[Spongebob]

My DS 8months is cutting back on his milk, but too much I think, hes only having approx 12 oz of formula a day...he has milk on his cereal and I give him yoghurts, and occasionally a bit of cheese, is this enough? any tricks I can try to get him to take more?

DD stopped BF at around 7 months .. only has a very small night-time feed now .. I make it up with milk / yogurt /cheese at every meal