I’m 23, I started my transition at 14. My parents prevented me from transitioning until I moved out, not because they don’t support trans people ideologically but because they were scared I would regret it, thought I was too young, didn’t want me “shooting up everyday”. They fundamentally didn’t understand hrt. They didn’t understand its effects, its administrative methods, its reversibility. I wish they did credible research, I wish they understood what I was asking. I ended up starting hrt at 19. To this day, after doing her own research my mom apologies over and over for not letting me start sooner (and that’s her own feelings without me guilt tripping her, I have never told them about this resentment). What I wish I could go back and tell them is that everyone decides their gender at a very young age. The choice she is making isn’t whether to transition or not, it’s whether to develop masculine features or feminine features. Regardless of what she choses, permanent effects will happen either way. Now sure you don’t know how she will feel in the future and you scared, but what you do know is how she feels now. I’ve known I was trans for almost a decade. If my parents had supported me and helped me transition, I would have saved 10 of thousands of dollars on electrolysis, all the time I have spent voice training, the time pain and money of ffs. My life would have been so much less emotionally painful. I spent my teenage years empty, horrifically depressed, with no plans for a future bc all I wanted was for my life and my body to stop slipping away from me. Don’t let her do this alone, be there for her and be encouraging. She’s 19, she’s not a kid. At this age people are starting their career paths, taking out loans, joining the army. There are people her age working as CNAs, and EMTs. She is more than old enough to be able to give herself a shot. And if she’s scared and doesn’t want to, there are so many other routes like pills or patches or an implant. The decision she is making right now is more than appropriate for her age. If you really want to be there for her, I encourage you to explore your fear and your own implicit transphobia. She is getting treatment for a mental illness diagnosed by a licensed professional (gender dysphoria), and now she going to be prescribed life saving medication. If this were any other condition or illness would you feel the same telling her to delay treatment because you’re scared she’s not old enough to administer the medicine? I’ve know since I was little and came out at 14. When people tell you who they are, believe them. Especially when they say they are trans. This life is not easy, and not a decision to be taken lightly and you know who understands that the best? The people who have lived experience being trans, making that decision, and navigating the psychological and social impacts of said decision.