My little girl just turned 3 months old last week and it seems ever since then, she won't eat nearly as much in one sitting as she used to. She would eat  6/7 ounces every 5/6 hours and now she'll only eat about 4 ounces at a time. She fights us and screams if we try to get her to eat anymore than that. She also is fussier throughout the day and is waking up more throughout the night. Is this normal for this stage and age?? I'm a little worried about her!