How many ml of milk does 17mo take each day?

My DS is almost 15 months. His usual routine is to have 150ml of cows milk when he wakes, for breakfast he has porridge. After his morning nap he then has 150ml cows milk (sometimes he does not drink it all) and the same mid afternoon. Before bed he has between 180-210ml of formula milk. Sometimes he eats quite well, other days he doesn't. Are we giving him too much milk? Should I cut out his morning or afternoon milk or both? Also trying to get him off the bottle and onto a sippy cup. He has water or juice quite happily from his cup, but up to now refused to drink milk from it.