Trans IS a mental disorder.
Trans is the incongruence between your gender identity, which is entirely comprised of your brain chemistry, versus biological reality. There isn't a tangible difference between being trans and experiencing gender dysphoria.
Is being transgender a mental disorder?
A psychological state is considered a mental disorder only if it causes significant distress or disability. Many transgender people do not experience their gender as distressing or disabling, which implies that identifying as transgender does not constitute a mental disorder. For these individuals, the significant problem is finding affordable resources, such as counseling, hormone therapy, medical procedures and the social support necessary to freely express their gender identity and minimize discrimination. Many other obstacles may lead to distress, including a lack of acceptance within society, direct or indirect experiences with discrimination, or assault. These experiences may lead many transgender people to suffer with
anxiety,
depression or related disorders at higher rates than nontransgender persons.
According to the
Diagnostic and Statistical Manual of Mental Disorders (DSM-5), people who experience intense, persistent gender incongruence can be given the diagnosis of "gender dysphoria." Some contend that the diagnosis inappropriately pathologizes gender noncongruence and should be eliminated. Others argue that it is essential to retain the diagnosis to ensure access to care. The
International Classification of Diseases (ICD) is under revision and there may be changes to its current classification of intense persistent gender incongruence as "gender identity disorder."
Transgender is an umbrella term used to describe people whose gender identity (sense of themselves as male or female) or gender expression differs from socially constructed norms associated with their birth sex. This includes androgynous, bigendered and gender queer people, who tend to see...
www.apa.org
Literally from the APA website. So while you answered the question why you think it's a mental disorder, the mental health community does not agree. As I said, mental disorders can be related to trans based on symptoms they have because of the various factors surrounding their situation, but being trans itself is not the mental disorder.