Five-year-old boy lives as girl in youngest case of Gender Identity Disorder

I stumbled across the article Five-year-old boy lives as girl in youngest case of Gender Identity Disorder when I was browsing on barstoolsports.com. The link goes to the original article posted in The Telegraph. After reading the article I could not help but think that 5 years old is a little young to be making long lasting gender decisions. Although it is great to see the parents and school system supporting this boy's decision, what if he changes his mind? Then the entire diagnosis of Gender Identity Disorder becomes less of a disorder and can be seen as a personal choice which degenerates the validity of the disorder, which is unfair to those who are old enough to know that they will always feel the way they do. I also am very surprised that it is referred to as a "disorder," to me the word "disorder" has a very negative connotation, meanwhile the rest of the story has a supportive tone,