Not all baby drinks the same, some might be small eater like my baby (5.1KG at 3mo, 90ml per feed). Although she’s on bm, many of them keeps telling me that she needs to drink 180~200 ml, why she drink so little bla bla (she is 11m and drinking 100~125ml since 8mo).
Don’t worry too much, all the numbers are just based on average and will not work the same for all. As long as your baby is healthy and active, good amount of diaper output and no signs of dehydration (dark yellow pee), then I wouldn’t worry too much.