This is going to sound REALLY bad?

I have two autistic brothers who my mom of course is very involved with. Shes always wanted to start a business and finally decided that she wants to provide a family operated weekend camp for children with special needs. thats a great idea and im very proud of my mom for putting this all together and at first i didnt think i minded helping cause im very good with special needs people, but im starting to realize that i dont want this at all. I love my brothers to death and i would do anything for them, but i dont want them to be the center of my world. Im not even 18, i want to do stuff that teenagers do. This is going to sound terrible but i want a normal life, especially since its highly possible that my own children will have special needs too. My mom is amazing and i know that my brothers situation has changed the way she lives her life and i know its harder on her than it will ever be on me. I dont want to hurt her, but i dont think i can do this. I just heard her on the phone she was talking about how im going to nursing school to be able to help out with the camp. she never even talked about this with me. Shes knows what i want to do and nursing isnt even close. Im seriously starting to get pissed off. she never even asked me she just assumed i was on board. I dont know how to handle this. What do i do?