Another ally here, and an old feminist. I am sure you are well intentioned, but I read this sub because I want to know about detrans perspectives and experiences, not for ally perspectives on how we got here or what it means. I think the OP is saying the political analysis doesn’t feel helpful or supportive, so maybe this isn’t the space to be making those arguments? There are other subs for that. To the OP I would say that not all allies judge or disapprove of trans identity. If I were coming of age today instead of 30 years ago I think I might well be on that path.

From your post and comments it sounds like your primary interest in the surgery is the belief that it will make you more attractive to men and more like a cis woman as a sexual partner. I would be shocked if either of those things are actually true, so those are ideas you should try to verify before proceeding. This is made more difficult because of the way the trans community prohibits open discussion of the differences between trans women and cis women. But the differences are significant, especially in the bedroom, such that for 99.9% of the population, trans women and cis women really are apples and oranges. Neither one is better than the other, but someone attracted to trans women is extremely unlikely to actually prefer a cis woman, or to leave the trans woman for someone with a non-surgical vagina. So if your goal with the neovagina is to be less trans and more cis ... I think you'll be disappointed. Men who love trans women love trans women, not cis women.

There MAY be some men who prefer trans women with a neovagina to trans women with a penis. I don't know why you'd want to date them, personally. Then again I wouldn't date someone who wanted me to get a brazilian.

Recent research I will link below shows that proportionally, a gay man is more likely to consider a trans woman as a partner than a hetero man is -- gay men are in fact three times more likely to do so. So your dating competition is again not cis women, but trans women and gay men. IF your dating pool is primarily among gay men, what are the chances they prefer a vagina?

A neovagina WILL change your sex life, probably dramatically, possibly for the worse. It will NOT make you more of a woman to anyone outside yourself.

In general, I think it's a bad idea to get extremely invasive, possibly disfiguring surgery in the hopes of pleasing other people. It's especially crazy to do for other people who possibly don't even exist.

Dating preferences research:

https://journals.sagepub.com/doi/abs/10.1177/0265407518779139?journalCode=spra

I’ve seen your pictures and you are a perfectly lovely human. I think you are suffering from a dysmorphia of sorts—you seem to have a really distorted sense of what you look like (and also a distorted sense of how much it matters). I’m 49, and 90% of people my age ain’t that hot. If I live to be 90 then fully half of my life I’ll be an old woman no one wants to look at. It’s okay. I’m good with not being beautiful. You gotta let it go. I know you have suffered a lot, but you CAN survive this. It isn’t fair that you had to go through this, but it won’t always be this painful I am certain. Loss is a huge part of life. It’s just what happens. I believe in you.

Medical transition is impossible to undo completely. You should be 2000000% certain it's what you want. And you should live a good while longer in the body you've got. At 18 you don't know which of your feelings are going to be with you in 2 years, let alone 5 or 10 or 40. Even if you felt this desire your whole childhood, it could resolve on its own in adulthood.

You are right to worry about how it will feel to live in that middle space. It is a source of angst and alienation for a LOT of trans people -- it shows up in detrans narratives, and it also shows up frequently in the stories of "satisfied" trans people.

In terms of the money and effort you've already invested, it is likely to be pennies relative to the lifetime costs and effort of medical transition. Being dependent on medical care for the rest of your life is an EXTREMELY expensive proposition, in dollars spent, and in lost work-time. I'd wager it is costly even in countries where the state pays for it; in the U.S. it's extremely costly. There is not just the cost of T and top surgery -- there is the cost of a hysto in 5 years, the cost of treatments to deal with side effects, complications, and the cost of recovery time for all of these.

If you aren't abjectly miserable in the body you have, it is INSANELY STUPID to undergo medical transition.

It's no more mutilation than a face lift, or intense body building, or breast augmentation or reduction, or any number of other things that we don't use the term "mutilation" to describe. That choice of terms does not help detransitioned people heal. So choose a different word.

In addition to the health impacts, she should know that binding can reduce her options for top surgery and can also impact how her top surgery turns out. Surgeons recommend against it.

Instead of prohibiting binding you might consider getting her a kinda larger one and allowing her to wear it a certain number of hours in the day, or in certain circumstances, if she promises to stop with the three sports bras. As others have said, the most important thing for her health and safety at this point is that she trusts you and feels able to talk with you about what she is going through. She is less likely to trust you if she thinks you are a transphobic bigot who doesn’t understand her and is just trying to control her (her peers and virtually all trans resources irl and online will assure her that is what your actions mean if she doesn’t come up with that interpretation herself).

You skipped some steps there, notably the one between transition and detransition, where you trade-in widespread admiration and social support for at best confused disbelief and at worst accusations like traitor/trender/terf.

For most (but not all!!) people I’d argue being trans is “less healthy” than not being trans insofar as being trans is highly medicalized generally and it frequently involves neurotic denial of some of the facts of one’s body and one’s history. For me, acceptance of your body in whatever shape and form is healthier than dissociation and/or self-loathing and constant striving toward an impossible ideal. Additionally, if your psychological well-being is dependent on the people around you validating your image of yourself, I think that’s unhealthy.

But I’d guess that detransition is probably not the right choice for someone who doesn’t want to detransition, you know? So if you are trans and don’t want to detrsnsition, just don’t. What other ppl do (or think) isn’t really your business.

Have you tried sharing with them anything about your experience? It seems like if you were to focus on your own experience—the good and the bad, and what changed for you over time, it is possible they could hear what you have to say without immediately going on the defensive. You risk having them get angry at you, but I think it might be worth that risk if you can plant even a seed of curiosity in them. It seems like if anyone could reach them it’d be you, since they presumably respected and admired you enough to follow in your footsteps the first time.

She had gender dysphoria and she socially transitioned, therefore she’s qualified to complain about the state of trans healthcare.

She is absolutely qualified to talk about the way the dominant trans narrative was harmful to her developing sense of self.

On how it feels weird: I don’t think you need to “identify as a girl” or “identify” with any gender category at all — you are simply a female-bodied person who likes what you like, dresses how you dress, and moves in the world however feels natural and healthy to you. Could thinking about it that way make this shift in your understanding of yourself feel less weird?

I don’t know how old you are but you sound too old for “girl” to apply to you in any case.

I don’t think happiness is found in finding the perfect label for yourself. And I think whatever label you arrive at will have little bearing on how people actually perceive and treat you. But if you like the sound of “tomboy” use that!