I started a new school in year 5 as this particular school went from year 5-12. I do regret not trying out for soccer but years later my old school friend said a lot of boys tried out for it and was very difficult and haven't lost sleep over it.

Other than that with what I know now I wish I had the knowledge and means to start even light weight training. I was paranoid about stunting my growth but avoiding the gym didn't help either.