[John123]

Hi,
is not the same breast and is not only testosteron the difference, there are much mode difference.
The sexual hormones not start work only in pubescent age, but also before, and the body situation is all different, the are different alignment of hypothalamus hipofisis axis and much more.
The body is very complex and the body of girls in prebuberal age prepare all for puberty, so is not only testosteron, is all body that have different condition.
If you think case of transgender child, the doctor often operate with drugs very early, and not ever, also if boy is very young, adult transgender body will be so good develope as woman.
Woman are woman and is ever the best, today we not have technical means for approach to result transgender body as body woman.
In some case there are very good results, but is very rare, and often start drug also young, but not is ever a warranty.
I think that much more possibility will be available, if will be more interest for this type of research, but maybe there are not much money for this, and there is not economical interesting that can attract researcher.
In any case is sad situation.