Its fine.. just go with your baby's flow. If she wants more, she will maybe cry after feeding or doesnt want to sleep. Thats when you know her intake will have to be increased as she is not satisfied. And its ok if she cant finish, dont force feed. Like adults, babies also sometimes just feel thirsty, or not so hungry, or very hungry at times. But my boy demands alot of milk. As ftm, i also followed the guidelines etc initially, but then after a while i just followed my instincts and followed his cues. When he was 1 month, 60 was not enough for him, he will keep on crying and i was also wondering what is wrong with him, so i tried increasing to 90 and he stopped those behaviour. He is 3 mths now and is drinking 150 3-4hourly. Even 180 at times! But just go with the flow.