Mom wants me to pay rent!?

okay so I just turn 18 and im currently looking for a job because I want to start being responsible. Next year im graduating high school and as soon as I graduate im going to a special effect makeup school. Anyways I'm just currently going to start to work and I was talking with my mom what things I should pay for when I have money. I told her I was planning on paying for the electric bill which every month the bill comes at $200 or $240 I have two turtles so their aquarium things take a lot of electricity!also I said I was paying for the Internet bill and the gas bill. And every week give her money for food and I also want to buy things for me and pay for my phone bill and try to save up for my school and a car. My mom works and her bf works too! They both make a decent amount of money to pay rent which is $1150 a month, and they're paying for both of their cars, their car insurance and their phone bills and food. So like I said I was going to pay for electric bill,internet bill,gas bill, and give her money for food. I also need to buy my turtles food, my dogs food.I shared room with my sister After I told her what I was going to payed for and why I had to save up money too for my studies and car. She said it wasn't enough and that I still had to pay rent even after I told her that it wasn't fair because I shared rooms with my sister plus Im not going to make a lot of money.My sister told me I was cheap and I don't know what do you guys think?