bigger-on-the-outside

I'm 20yo and can't really remember a time where I wasn't huge.
I wore adult sized clothes from the age of 5 and can't even remember a time I wore proper kids clothing.
I'm terrified of the future and what it could hold for me in terms of diabetes and premature arthritis unless I do something now.
I'm only a month away from surgery but am scared of afterwards as well, like not eating the things I want for weeks and have nothing but broth for a while.
I can only hope that I'll get through it with my head held high and not too many years shed.