Well, the nature of just what is and isn't my "authentic self" has changed a lot over the years. In the past I thought it was immutable; now I know it isn't... and I also know it isn't what other people say it is, but what I say it is that is most important to my existence.
I realized that how I felt about myself was paramount to maintaining a healthy mind so as not to fall into an extremely unhealthy pit or rut of despair. My 'authentic self' certainly isn't a woman, I know that now. Far too much evidence - despite the shape of the body - that this is the case. Shape means nothing. What feels right and what is my natural inclinations that cause me relax when they are expressed is everything. As a "woman" I had knots in my shoulders from how nerve wracking and grating that existence was. As a man, I feel an absence of discomfort and anxiety. This isn't a conscious choice, just a bodily fact. And I'll go with that over anything anyone else says about what I "am".
So what does the dysphoria feel like...? It was kind of like... sharing a cell with someone I didn't get along with at first. You go through the motions of initial dislike, then deep hatred, then finally you try your best to simply ignore the person and live your life, but ofc they can never go away. They will always be there to stare at you in the mirror, remind you when you see a body like your own on TV, and they'll be there whenever anyone reminds you how wonderful you should be feeling about your birth gender because they assume you like it and identify with it. The very best you can do is turn away and try not to look at them. I remember my days as a teenager abjectly reviling myself. I would sit up asking why the hell I had to be born this way because I knew it was preventing me from having a normal life, from enjoying and experiencing many of the things others can enjoy without effort. So it feels like hate, it feels like suppression, it feels like being denied a proper life, and it feels like bitterness because of it. Ultimately it all cumulatively builds up to the usual things like anxiety, social anxiety, depression, despair. It's a complicated set of interlocking emotions not easily put into words, but it absolutely feels like a chain hooked into your back keeping you from moving forward, in most directions... or perhaps like being outside in the cold looking in at other people enjoying things you never can and never will.
I felt at some points like perhaps I was defying my reality, but then I learned that reality is as much in the mind as outside of it. Especially when it comes to happiness. What I do to my body is nobody else's business, nobody else has a stake in it, so what is there to lose?
But if you only feel mildly dysphoric about your gender, you'll be like some people I know who seem to fall more in the middle of the spectrum and are less tormented by not being one gender or the other. The absolutism of my early years was a big problem and now I know it was all for nothing, really... most of the time you're free to be whoever you want to be and as long as you don't put yourself in trouble's way, I doubt any "transgender police" are going to find you. At least not if society remains the way it is here. It would have to be some Nazi Germany-esque social cleansing scenario that would have me worrying; what people may say or think doesn't worry me, only what they may do. And most of the time they don't do much, or cannot do much to hurt you, even if they disapprove. Sticks and stones, right? I only care about the sticks and the stones, and keeping out of dangerous situations. Other than that, nobody bothers me about my trans status.
The idea of being a man never appealed to me especially. It still doesn't especially. It's already who I am inside, there's no allure, nothing surprising about it. I don't feel like a transitional person - I've always been that person, with a mis-formed body.