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.