There is a social definition of what depression is. You can't self report that you have depression if you think depression is a blue bicycle stored in a shed. You have to be self reporting symptoms from the agreed current definition.
Yes -- and, the thing is, no-one has yet defined 'wrong sex/gender' as, say, depression and schizophrenia are defined & revised.
Let's time-hop to a few years hence, when there is a suitable questionnaire developed by trans people and the relevant experts. To benchmark the criteria for special treatment, medical and legal, this questionnaire would have to be tested on the population at large.
And this where I suspect we might have a problem.
I'm one of the many women who doesn't recognise a gender identity in myself. In fact, I bridle at the very concept of gender and the ways it restrains people based on their reproductive equipment. I am quite sure that huge numbers of (cis) women & men lack a gender identity.
So, passing over questions about whether I preferred tea sets or tractors as a child (neither, and had both) and feel more myself in a dress or trousers (neither, but mostly wear trousers), we might get on to more searching issues such as whether I'm happy with my sex & gender. Well, not really; "used to it" would sum that up. Have I ever wished I were the other or another sex? Yep, often! Have I ever resented my genitals & reproductive equipment? Hell, yeah! They're often messy and cause pain. How did I feel during puberty? Scared, angry and confused; doesn't everyone?
This is a strangely rambling post, to be sure, but perhaps my imaginary diagnostic test will help to show how you can't evaluate a human condition from a single perspective. Also, that pretty well all such evaluations must, by their very nature, be pinned on social constructs.