I agree whole or partly with everything you said except this last part.
Yes, it is true that those who transition have several mental health comorbidities including depressive disorder (70%), anxiety (63%), post-traumatic stress disorder (33%), attention deficit disorder (24%), autism spectrum condition (20%), eating disorder (19%), and personality disorder (17%)
(1), that later once resolved cause them to de-transition.
However, I'm not talking about people transitioning medically, I'm just talking about outward appearance and forms of address. If doings these things helps manage some of those above mentioned mental health issues, than what really is the harm? If your child's psychiatrist came to you and said "your 15 year old is at an extreme risk of committing suicide, and I believe allowing them to identify as the gender of their choice will help reduce that possibility", are you going to say "no"?
And if you heard from your own kids that a friend of theirs's at school committed suicide because that kid's parents wouldn't let them be called by their prefered name and dress the way they wanted, would you think "Well, their parents know best. I guess suicide was for the best".?