Saying HRT is totally safe is pretty intellectually dishonest, as anyone with a basic grasp of endocrinology knows that adjusting something as biologically-pivotal as sex hormones comes with drastic physical changes, some of which may not be in your favour healthwise. In the case of FTM hormone therapy, longterm use can result in vaginal atrophy and, more rarely, an increased risk of uterine hyperplasia or cancer, and it is also common to have an increased incidence of cardiovascular diseases. In short, it comes with all the risks of anabolic androgenising steroid use, which no one would say is completely safe even if you can use them responsibly.

For MTF hormone therapy, oestrogen use can trigger autoimmune diseases that were previously suppressed by natural testosterone production (hence why women in general have a far higher incidence of autoimmune disorders), and so that can cause anything from thyroid destruction, rheumatoid arthritis, eczema/psoriasis, nerve degeneration, on and on. Women also have a higher incidence of Alzheimer's/dementia because of the lower testosterone and resultingly lower glucose utilisation, so one puts oneself at higher risk of developing dementia later on in the long term. Similiarly, there is also an increased risk of osteoporosis, especially for those who also get an orchiectomy.

For both, there seems to anecdotally be an increased risk of developing diabetes - in the case of FTMs, from wanting to eat much more on testosterone but not increasing physical activity in proportion, and for MTFs, eating a lot of the same junk they did on testosterone which results in rapid fat accumulation due to tanking testosterone and thyroid hormone by drastically raising oestrogen.

Whether or not they spend a lot of time on left-leaning social media venues is the biggest red flag to me, as I have seen time and again a lot of detrans individuals talk about how they were influenced by the trans internet sphere in such places, especially young people. So there is a good chance their "transgenderism" is more about trying to fit in with or ingratiate themselves to a certain idealogical circle on such sites without realising either the medical toll of actually transitioning ahead of time and/or having any real grasp on what it means socially to be the opposite sex.

Sunlight stimulates the production of vitamin D, which is an important hormone that reduces inflammation and it also helps remove excess calcium from the blood (which in the long term will lead to cardiovascular degeneration up to atherosclerosis). People with pretty much all stripes of mental disorders, including depression, have been found to have high amounts of systemic or brain inflammation, likely because said inflammation is ultimately what leads to the mental illness. So getting out in the sunlight, going on a walk, and otherwise not sitting hunched over staring into a blue light for many hours in a day will all reduce inflammation and improve blood flow, and that improved well-being leads to improved mood.

I was on testosterone for about the same amount of time, but I started a bit later (started at 23). I have been off it for 7-ish months and hormone-wise, things seemed to have gotten back to normal, though it took a painful 5 months to get there even with tapering. Depending on the kind of testosterone you used, it could take longer or shorter, and the younger you are, the easier the process should be. Even if hormones go back to where they were, though, some things will be irreversible or mostly so. Facial and excess body hair, for instance, won't go away without laser removal. Some regrowth of scalp hair is possible, though others won't regrow their hair — probably depends on genetics, your lifestyle in the past and going forward, and when you lost the hairs. Some people evidently get some lightening of the voice but typically you shouldn't expect that to go back to where it was pre-T.

There may be the option of breast implants and laser therapy for the body hair — but in many instances, insurance won't cover that for detransitioning people, so that might not help you immediately. What can be done immediately is to start working on ways to not compare yourself to others in order to feel validated or confident in yourself. I'm not fond of my top surgery, though mostly from the scars having become unexpectedly unsightly, not so much any diminished attractiveness to men — but I have learned to be confident about it even so in not caring what others think about it, and it doesn't occur to me to feel jealous of/compare myself to other women much.

I only started to try to get off testosterone at seven years as well. I don't know about others, but for me, that just so happened to be when a lot of the negatives started catching up with me (hair loss and terrible skin), and I guess consequentially, looking more like a diseased man and less like a teenager seemed to give people more license to treat you poorly. It was mainly the aesthetics for me, though. I imagine if I had been able to take care of myself better or notice the hair loss sooner, would have desisted sooner or later than seven years.

Non alcoholic fatty liver disease is usually caused by excessive refined sugar consumption and fat deposition likely exacerbated by eating a lot of seed/vegetable oils. In other words, it has a lot to do with obesity, which testosterone would have actually helped reverse/control given it promotes lean muscle mass and improved glucose utilisation and fat burning thereby. I have seen some FTMs say they feel like eating a lot more on testosterone, though, and without eating clean foods and/or lacking physical activity, that can promote putting on weight and the pathogenesis of NAFLD. Fortunately, it is reversible or otherwise controllable by changing diet (cut out processed foods which have a lot of vegetable oils and sugars, and also reduce processed carbs like flour/bread in general) and introducing more exercise.

Someone else pretty much hit the nail on the head in that what you seem to describe of "possession" being what it likely feels like to be caught up in a zealous ideology. I've seen people caught up in destructive cults describe much the same in retrospect, including being severed from past associations. It wouldn't surprise me if a good amount of trans people today fit that description as far as being swept up in a toxic and irrational form of gender politics. I personally cannot relate, though — I was never into trans-politics or the internet scene thereof, so my choice to transition was made by myself for myself, and I've never felt besides myself, so to speak.

I think in a lot of cases like yours, it is not actually so much a desire to be one gender or the other so much as just wanting to fit in well or be accepted in some social circle (or in normal society as a whole). I live as a man because I certainly can't pass as a woman and it is slightly easier in such circumstances - but I don't pass too well as a man, either, evidenced by the constant shit/disrespect I get for looking perpetually like a teenage boy. That being as it is, I realise what matters most to me has been just trying to find a place where I at least wouldn't be abused or ideally, where I would actually be accepted for who I am, whether as a man or a woman. Still haven't found it yet, though, and that sort of social instability feeds into the kind of emotional fugue you describe.

I guess one of my "uncles" who is somewhere over 70. Don't know of how well he fits as a "success story," though, because he is intersex, with the same condition as I have, and he's flipped a couple times in his life from identifying as a man or a woman or back again. Sounds like gender doesn't really play a huge role in his identity, so much as it is just a masquerade with certain perks and which depends on how he feels like at a certain time. That's how I feel about it, anyways, and what I would guess is going on with my uncle, too. As such I'm not sure if I ever actually qualified as transgender, and I'm not sure if he would, either.