Hi BlackWolf and welcome to the board.
Wow.... your story resonates with me so much. I was your age when I started doubting. That was back in the late 1970s (yeah, I'm getting older... something the Watchtower said would never happen... hint #1 they are full of it).
I'll tell you what I did and I hope it helps. I secretly planned my life. It is good you have a goal of Art school. Do not give up on this. Look into how you can accomplish taking this after you graduate 'high school' (or the equivalent). My plan was to go and study Computers in College. And I did it. I just had my 30th career anniversary. There IS life outside of JW-land. ;0)
About money... my folks never saved for my education so I started working as a teenager. I babysat and got a part time job at a convenience store. Whatever you do, start saving your money. There are usually financial programs available to assist students with post-secondary education. I had to get a loan from the government in Ontario, Canada to help with my schooling. But I took it. AND... once I graduated College and got my job, I paid that loan back. One of the key things I did was to move away from home to go to school. It was a fun adventure. I got away from my parents trying to influence me with JW crap. And I got very busy.
You CAN do this. Start planning now. Look into how you can do this. And have fun!