Just to reiterate: I define trans women as women. My point was that TERFs don't. And one of their arguments is about the logical endpoint of accepting trans women as women; they argue that it would require cis women to admit into women-only spaces anyone who simply says they're a women, even pre-op trans women who don't appear as stereotypical women (clothes make-up etc.). The consequence of which would be that any man could enter a women-only space simply by saying they were a woman. This is what I was getting at when I spoke about 'just saying so', not that idea that there's nothing more to transgenderism.
Nor am I saying that you're 'making it up.' I have no doubt that you felt trans for years before you even knew what trans was; I don't think even TERFs would deny the existence of people who identify as transgend; rather, they deny that believing you're a woman makes it so.
Ultimately, it appears to me that there is not one generally accepted definition of 'woman.' There are many competing definitions, most of which have strengths and weaknesses; I have adopted one that includes trans women, not becasue of the compelling logic of so doing, but becasue of the harm that arises from excluding trans women. But, I'm not sure that, as a man, I feel comfortable trying to force women to make the same choices as me. This is not least of all becasue it's an easy choice for me; I don't know how I'd feel if I felt that my sense of self would be harmed by a redifinition of what I am, or, if, say, my life experiences were such that I was scared of the practical consequences of adopting a course that could allow men to 'infiltrate' women-only spaces.
I think that part of the problem is that people on both sides adopt extreme positions, and make little effort to attempt to empathise with those on the other side. I can understand the pain it must cause trans women to be excluded by other women; I can also understand why some women become angry at the idea of being bullied by people they consider men. I am hopeful that, in time, a more reasonable dialogue can take place, which ultimately results in all people accepting trans women as women. I don't think Greer has helped with that; nor do I think have some of her opponents.