I think this is an apples and oranges example. Phimosis is a directly observable, quantifiable phenomenon. Feeling like you're in the wrong body is not.
I'll ask you the same question I just asked: How would you categorize trans? A disorder? A condition? ...
The same way that I would categorize gay. I know that I find men attractive, and do not find any females attractive, ever. I am a person who happens to believe that the mind is the product of a brain -- with which it interacts and thus is to some extent self-shaping -- and that the only actual "person" that I can be is the one that my brain/mind/brain thinks that I am. Therefore, I am a homosexual, because the object of my sexual attraction has the same physical body parts that I have. What I do not think is that there is somehow this "person with a disorder or condition" that makes him think he is attracted to males sexually, but isn't -- somehow -- really: that he just "imagines it."
Now, I don't know you. I don't know how you see yourself. If you are male and attracted to females, do you suppose that you might just have a "condition" or a "disorder" that can somehow be corrected while still leaving you as the same person? Do you imagine that there is any way that you could be persuaded to change that sexual attraction to the other gender? I don't mean submit, like perhaps for large amounts of money -- I mean really change that orientation, permanently. I'm willing to bet that you do not.
At the end of the day, I think one of the things it means to be human is the mind itself -- which we know to be quantitatively different from every other animal on earth, and qualitatively different from the vast majority of them. Take away my mind -- and while you may keep my body going with a vast array of medical bravado, I, the person who calls himself EvangelicalHumanist will no longer be there, will no longer exist.
And so, the transgender person is the person that they think and feel themselves to be -- not their body. I grant you, I don't know how I would cope with that, but I do note that transgender individuals have to do exactly that -- cope -- every day of their lives and in every (sometimes hateful) situation in which they find themselves.
And no, that is not a "disorder" or "condition." It is a brute fact of the brain/mind/brain that makes them to
BE who they are.