"A true 'disorder' would be for someone to go through a traumatic experience and not have an adverse psychological reaction."
People react differently to life is true and just because some people have a harder time dealing with certain circumstances doesn't mean they have a disorder is also true. But your statement is outrageous to claim that someone may have disorder because they do not respond in kind. Some people are stronger than others and they no more suffer from a disorder than those who are weaker.
The idea that everyone should act the same is the problem.