I agree that just saying something is so doesn’t make it true. So saying you aren’t cis doesn’t make it true.
If your womb and vagina are what make you a woman, then anyone without one of those is not a woman in your opinion? I have a vulva but no womb. How am I different from women either a) without a womb due to hysterectomy or just being born without one; or b) born with a womb that no longer works due to PCOS, menopause, some other condition, or all of the above? The only differences are things you can’t see, such as what the doctor happened to observe when I was born and what internal organs I may or may not have.
By the way, I was assigned male at birth and yet legally and socially I am considered female: my ID, Passport, and birth certificate all have an F on them. All people treat me as a woman, relate to me as a woman. When my wife proposed to me, she knew she was proposing to a woman. In other words, it’s not just my word against everyone else’s; It my and everyone else’s word against yours.