my baby was 42 days old ... from born he was talking formula milk for some hard situation.. now he was started taking my feeding from 4 to 5 days.. bt still he can't full this tummy he always want some formula milk after feeding.. although i have a good feeding flow.. now i want to know that if he was taking 60ml for each time of feeding.. that how can i calculator that how many minutes of feeding fullfill his tummy????