If you think your reply sufficiently responds to my own, then you didn't read my post carefully enough, because I already addressed the catch 22 aspect of the situation. Since you seem to have be having difficulty seeing it, allow me to expand on that aspect of the problem.
The catch-22 is: you cannot predict the effects of puberty on a child who presents as trans before puberty. Puberty may remove the trans presenting issue, or it may not, but you cannot know ahead of time unless you're going to claim that science is capable of perfect prediction, which it is not now nor is science likely to ever possess that capability. Regardless of any scans done on someone's brain before puberty, any tests of their endocrinology, or anything else, science simply is incapable of perfectly predicting 5 years in the future of an individual. There are simply too many variables to consider.
So, faced with this catch-22, we as a people have to do a cost-benefit analysis. We have potential harm, and potential benefit.
-The potential harm is that the child will be permanently disfigured and rendered incapable of reproducing. Keep in mind that reproducing is the primary drive governed by our biology, and taking that ability away from a person is a tremendous harm to that individual.
-The potential benefit is that the child will feel better about themselves later in life, but this is not guaranteed. And before you cite the scientific study to claim that it is guaranteed, a study CANNOT provide a guarantee. It can only measure past results, not future outcomes.
Also, consider the magnitude of the potential benefit in this situation. Here I'm quoting from the last line in the study you keep quoting: all of 70 eligible candidates showed improved mental health and general functioning. This is the best case scenario: improved mental health and general functioning. Not normal, not satisfactory, not 'great!', but 'improved'.
Improved from what? Suicidal? Gloomy? Irritated? Anxious? It's inherently a relative and shifting standard.
We also know that it is possible to have great functioning in life after puberty is completed if you don't go through with hormone blockers before puberty and you present as trans. How do we know this? Because of you, Vanessa. Your life proceeded exactly this way, and you claim to be fine. So, it must be possible, unless you're an extreme outlier which I doubt.
So, faced with the possible harm of permanent damage to a child who is not old enough to decide for himself what is best for him, with the possible benefit of merely 'improved' mental health later in life and knowing that 'improved' and 'totally satisfactory' mental health is possible later in life WITHOUT undergoing puberty blockers early in life, we must conclude that the potential harm outweighs the potential benefit AND that there are viable alternative methods to achieve the same result.
After running this cost-benefit analysis and weighing the ethic of protecting children who cannot be responsible for their own decisions from harming themselves or from being harmed by others as higher than the ethic of improving the mental health of adults, the ethic of protecting children wins out.
TL ; DR : Until such time as science or some other force is capable of perfectly predicting the future outcome of any child below the age of puberty, it will be unethical to allow a child to undergo puberty blocking hormones in an effort to improve their future mental health.