Why do I get so annoyed?

My niece is planning to home school next year and she is going to stay over at my house. My mom cooks for them every time they come over and she has been using the organic meat that I am trying to keep a stock pile of because I don't want to constantly have to go to the store plus organic meat is expensive. My niece eats a lot and it's just my mom and I at my home. My mom can't work so she stays home and takes care of my nieces whenever my sister needs it. I'm annoyed at the fact that my mom uses my food to cook for them when my sister doesn't even buy them organic meat. Also I look forward to being alone in my home and now she is going to home school and probably wants me to play with her but I value my quiet time a lot plus they always want to be in my room and just mess up my bedsheets. I'm already getting a little stressed because I feel like I have to pay for food it's just me paying all the bills, food, utilities and HOA

Why do I get so annoyed?
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