The more I ponder this thread the more it merely illustrates the inherent problem people that are not us, have in being able to understand us.
Asking me, why do I want to be a woman, is as pointless as asking me why I want to be Canadian.
My as well ask if I like being Caucasian as well. I also don't mind being a Terran.
But the questions that have me the most at odds are 'so how long have you known [insert some specific detail here] ....'
I was born in Lachine, but hey that was where mom had me and nothing else. I have never been back to my knowledge, so ah I have NO memories of it. I lived in a small town in Quebec for 5 years. I have precisely 3 mental images, and nothing else. A scene of my sister in a snow suit and stuck in some mud of a new house site. My brother playing in a small boat that was sinking at the riverside end of the street, and this massive field and a factory on the far side at the end of the street and a train track on the far edge. Turns out the factory was my small mind's way of understanding my older brother's grade school. That's it, 3 images in my first 5 years.
I have almost nothing from my grade school years in the equally small town I am still in since 1967. So that is my preteen years and really next to nothing. I recall playing in the dirt with Tonka trucks and Matchbox cars with a childhood buddy who I broke up with at least once a week

I remember playing in nearby streams. And I climbed all the trees.
Most of my years from teens are best summed up as in a book, be it library, local stores, my room.
Hell I have lived enough years that a lot of the first half have largely ended up as badly faded and grainy at best

It takes some serious effort just to remember the 90s and I usually get it wrong.
How long have I known ..... heck I have trouble with last week most months

I want to 'look' how I feel for the same reason I want to be in a 20 x 20 room listening to music too loud while breathing in the smell of lumber and making some article of woodworking. It's because that is what would make my soul sing.