Puberty didn't agree with me one bit - but I was able to remain stable just enough to function until it came time to get on "the pill" (at 17).
Then it all went downhill from there. Non-functioning, unable to hold down a job, almost institutionalized, a cocktail of strong meds (anti-depressant, anti-psyhcotics, mood stabalizers, etc). I was told that I'd never function well enough to be independant as an adult, I'd always want to kill myself, and my "mental fog" was permanant. They said I'd be in and out of institutions, I'd only get worse, and I'd need therapy and meds for the rest of my life.
I kept saying the estrogen didn't agree with me. They wouldn't listen. They kept telling me I should feel much better with "normal" levels of female hormones. Apparently only getting "spotting" for a few days every 3 months ment I was hormonally out of whack, and needed to be "corrected" (but it wasn't grounds for believing me about estrogen not being compatible with my system).
I tried various different pills, but spent the most amount of time on an estrogen with testosterone blockers combo. It brought about lots of horrible physical changes (and a normal XX person's cycle of HELL).
I went off said pill about 18 months ago - and started feeling clear headed for the first time in years.
About 12 months ago I completely weened off the other meds.
I didn't come out and start transition until about 9 months ago.
I've had no medical supervision for any of this... a shrink would probably chuck me in a padded room for what I've done

.
... but the proof of my concept is in the results. Since stopping the pills (all of them) and starting transition, I've been more stable than I ever could have hoped for. Functionality wise, I'm within normal parameters. I haven't even thought about self harm (let alone suicide) in 18 months. I haven't even been depressed. Angry and dysphoric within the parameters of GID, yes. But it's been different. I can pinpoint what's wrong, and I can deal with it.
According to the shrinks and doctors I've seen - this isn't possible. Yet here I am... grabbing life by the throat and shaking it like a British nanny

.
I still get a little twitchy in some social situations, and I'm still outright eccentric by normal standards. I'm still very uncomfortable in my own skin (it's purely a physical thing, and I can now identify where and why). But hey - by comparision, that's just small stuff (that can be mostly fixed via medical transition).
I spoke to an endo nurse (of 25 years experiance in an andrology clinic) earlier in the year. He said that in his experiance, it's not unusual for FTM's to be "incompatible" with estrogen. Of course, he said there hadn't been any formal studies done that he knows of, it's just what he's seen on the job.
I know we're told not to expect any mental issues to vanish with HRT, and for some part I'd say that's true. But I find it very hard to believe that T doesn't improve mental stability for at least some FTMs.
I'm pre-T, but given what E did to me (or more what going off it, dropping my E level through the floor and shutting my repo system back down did) - I'd like to think I have some idea of the mental changes that will likely happen on T (expecting similar but "more" if you know what I mean

).