The most important thing is anticipating what concerns
she may have. Is she religious? If so, you might want to address those conerns with the verses from the Holy Book she reads. Would she be more concerned about the dangers of what may happen to you physially? I would touch on that. It doesn't have to be super long, but let her know you are aware of such medical concerns (as the doctors are) so you will be closely monitered by your physician while taking T (if that's what you want to do). I would also emphasize how you came to this decision. I suggest giving this great detail as I personally see that as the most important thing so she won't think you just thought about this randomly
Also let her know that if she has any respectful questions, then feel free to ask as that shows how prepared you are for this. I think you will do fine, Dean.

You're very articulate.
Best of luck!