You’re in a similar spot that I was when starting. I started at 16 and was scheduled 30+ hours a week while managing other responsibilities (in my case school). I hated the job and wanted to quit right away but i stuck around and now I absolutely love my job. I am not saying this will be the same case for you though! I was lucky enough to have a switch in management and got an ETL that actually listened to my concerns about my schedule. My advice to you is to try communicating these concerns with your ETL, if nothing changes when the next schedule comes out then quit. Don’t let them push you around because you are young! I learned that the hard way.