If she is not drinking well, losing weight, milk spits then you should be worry. Otherwise you can see the milk intake pattern, increase milk ml where necessary and to take note the interval of milk intake like a gap of 2/3 hrs. If you are training her exactly the same way as IFC and only direct latch at home/bedtime, then it should be consistent as to school. You can always share your routine or to check how the feeding gap is in school.
My 2 (close to 3) month old also only drink around 300mL-400mL during day time. In fact her total 24h intake is only 500-600mL. PD said to ignore the “guidelines” and just feed on demand. Not all babies drink the same amount. As long as weight gain is good, wet diapers are good then all is good.