Think bigger.
Get a FIFO job on the mines for example, even if it's just driving trucks to start with. Get to live away from the parents for decent stretches at a time, get to use all the free fitness gear and free meals and board. And the income boost will give you investing options you can only dream of right now, if you save the increase and put it to work. And you might even meet some nice men, or not so nice ones if that takes your fancy!
Set stretch goals for how your income is going to increase dramatically and then do everything you can to achieve them. You've proven you can do it with your weight and health (which I applaud you greatly for - a fantastic achievement and the most important priority!). Now it's time to do it financially - your investing options and your eventual results in 27 years time (and all along the way) vary exponentially with your income, so do whatever it takes to get a higher income! And I don't mean umpiring!
You sound very much to have imposed a heap of unnecessary assumptions and constraints on yourself and your future. You have no real ties and no limits other than those. So my 2c worth is to do whatever you can to break free of them and think bigger! The worst thing that can happen is that you just stay where you are now so there is really nothing to lose...
Hope this helps!