A guy who had been working in an andrology clinic for 20 or so years came to speak to our FTM group one night.
One of the things he said, is that the brain has to be "running on the right fuel" to function properly. It's common for T people to feel much calmer and think more clearly after starting HRT, and he's seen it happen with pretty much every FTM that's walked in the door (apparently part of their monitoring is asking you a series of questions about your mental wellbeing and any mental changes before each shot).
He said this may be due to the hormone levels being monitored and tweaked, and the same "relief" thing happens to genetic men with hormone imbalances that they treat.
Apparently, a surprisingly large number of cis-people have hormone imbalances at some stage in their lives too, and "it's a pity they just see it as normal, because they'd feel and function so much better if they got it seen to".
It's nice to know I'm not the only one who rages out! I think it's part mental, part hormonal. I know for me, things got a heap better when started doing the social side of transition, but there are still times when I feel the E levels spike and go all weird (I refuse to say girly. I don't go girly. I go weird).
Mentally speaking, my "weird" is a mix of rage, self doubt, mental "fog" (unable to think straight or concentrate), depression, emotional instability coupled with much stronger emotions and social phobia. Also, my self confidence takes a massive dive.
It is horrible. It was worse on E and T blockers (and they weren't even that strong, apparently) - I honestly thought it was permanant, there was no way out. After all, I was being told I had normal female hormones now, and this was "how I was supposed to be feeling"! The last remnants of my semi-rational mind had me ready to eat a lead lunch at cafe barrel.
That's what my brain equates with "being and feeling female". I'm sure MTF's have a similar association with T and "feeling male". It's not a sexist thing, it's just body and brain at war.
I don't know what it's like to be female. Not a real one, anyway. I pretended for a long while, but I could never fit in. Not on the inside, and that conflict always it showed on the outside - no matter how hard I tried to hide it (I was never accepted as one of them either).
What's it like to be a man (to me)? It's almost too easy

. The world makes a lot more sense. Being accepted and fitting in is much easier than I ever expected - I just have to say, think, act and do what comes naturally. I don't feel a "power" as such, but I do feel a huge increase in confidence and relief from finally being able to be myself, and having the world react in a positive manner!
Sometimes I can revert slightly in difficult situation though - but I think it has to do with being used to putting up a front for so long. While finally being yourself can be a massive relief, it can also leave you feeling a bit naked at times. If people dislike you, it's
actually you they dislike, and not who you're pretending to be. You've got nothing to hide behind anymore.