In psychology, there isn't a "normal" mental makeup. What tends to become categorised as an illness or disorder is when a person is having difficulty/conflict with their self-perception or their perception of the world around them.
If someone is living a reasonably contented life even though they like to dress up as a different flower for each day of the week, it's pretty unlikely that they will be diagnosed as having a mental disorder.
To take an opposite scenario, I would bet that if every person here who considers themselves to be normal and reasonably well-adjusted was to visit a psychologist, that professional could identify a number of traits that are typically associated with mental disorders and could cause problems if those traits became stronger / more prevalent in that person's thoughts and actions. Mental health professionals have to go through a lot of training, examining their own mental foibles and biases so as to ensure that their own personalities aren't colouring their ability to accurately diagnose and analyse others.
Saying that transpeople all suffer from mental disorders is about as helpful as the multitude of people who have claimed that homosexuality is a mental disorder (it was professionally considered to be that and in recent decades not to be
due to an increased understanding of sexuality). Homosexuality was often considered to be a mental disorder because of the environmental factors surrounding it: Gender perception, religious dogma, lack of understanding of sexual diseases, gay people being violently targeted or regarded as outcasts resulting in behaviour that will almost invariably be the mark of mental illness, e.g. attempted suicide. Many trans people will have had similar problems within society and/or will have had difficulty with their gender perception which may be resolved purely through therapy, and some may be more comfortable with their identity and self-perception after gender reassignment surgery.
Sexuality comes in infinite variations. Various representations of homosexuality provide obvious indicators about how some people perceive themselves that definitely blur the lines of gender demonstration. An unrelated example is how some guys like to wear womens' underwear and don't take it any further than that.
So I find your idea amusing that while there's infinite variation in sexuality and how people express themselves, there's a black line on each side of anything that could be labelled as transgender-related and marked as BAD.
But considering your ignorance yet willingness to demonstrate your shortcomings in
basic female biology, I guess I shouldn't be surprised at your absolutely firm belief that you're correct on this topic.