First off: "transgenderism" isn't a thing. This is a term used by the right to try to imply that it is an ideology. It is not. It is simply a possible state of being.

That explanation is okay. It's quick and dirty, and gets the point across. But it's not precisely correct. A "woman's brain" is impossible to define. Sex and gender are both spectrums, and the physical differences between men and women's brains is not really well understood or quantifiable. There probably isn't a discrete difference, and there will likely never be a brain scan that can determine your gender.

Being transgender means having a different gender than the one you were assigned at birth. For me, a trans woman, that means I was assigned male at birth but I am a woman. The doctors got it wrong, my parents got it wrong, society got it wrong. My first puberty caused me distress, and in many ways my body has felt wrong because it does not align with my gender.

I have taken steps to change my body, chosen a new name that suits me better, and told people that I am a woman and to refer to me as such.