My niece gets on my nerves. She comes from school saying "I'm hungry" or "What is there to eat" she…

My niece gets on my nerves. She comes from school saying "I'm hungry" or "What is there to eat" she doesn't eat at school cause she "doesn't like what they have". Well you better eat that shit cause I ain't fixing you something when you get home or you ain't eating up all my baby's cereal and milk cause you chose not to eat at school. Then when we cook dinner like awhile ago I made my sons plate first like always and she comes and says "just to let you know I'm not hungry so don't fix me a plate, I'll eat later" I'm like and there won't be nothing to eat later!!! Like you eat when we cook you not about to eat all my babys stuff up. I wasn't making her a plate no ways. She's 13 years old she's capable of doing it herself I ain't her damn mama. Then she asks if "there's any fruits" I told her no cause she's not eating my sons stuff up and I'm tired of all my sons milk being gone after only 2 days. It's ridiculous. My brother needs to buy her some foods she can microwave on her own or something cause I'm about to put duct tape on my sons milk lid and cereal lmao