I find this kind of discussion a bit strange. Some of you are saying you're not women; you are people. Well define a person or a human being in the same way that people are attempting to define woman. What makes a human a human and a bird a bird. Well a human has two arms and a bird doesn't. So am I now prejudiced? Am I saying that a child born with two arms is a bird? It just gets ridiculous.
We know, when a child is born, almost always, if it is male or female by looking at their genitalia. In the few cases where it is unclear, experts try work it out by gathering further information that would not be obvious at first sight. Is anybody really suggesting that mothers don't know, most of the time, what sex their baby is, and are waiting for the child to be able to speak so they can express an opinion on the matter?
Now, it may be imperfect. There are many differences between males and females, particularly in the face. But sometimes there are women who have a male type tilted forehead, but then they might have other female features. It is an overall combination of outward features, so no, somebody who has a hysterectomy is still a woman because they have lots of other female features. You can't base it on one physical feature alone. There is no perfect way of doing it, but there are a wide range of different features, that when combined together make men and women different.
Pointing out the imperfections in defining women by biological sex isn't in itself a justification for saying we should define it based on people's gender. You need to show that the characteristics of gender identity are more reliable than the biological characteristics.
But nobody is prepared to do that. I can't come along and critique the idea that gender identity makes women rather than biological sex because nobody will say what the characteristics are. I can't say that your concept is wrong because I am a woman and I don't feel X,Y and Z. You may as well be saying what makes a woman is if they feel warmly towards snorles or not. And then refuse to tell anybody what a snorle is. It is an absurd argument.
If you cannot define what gender identity is, then I cannot say if I am a woman or a man, or if my children are male or female, because you are arguing for imposing on everyone group identities that have no defining characteristics whatsoever. What is even the point of it? If gender has nothing to do with biological sex, you may as well say that you are going to set up segregated prisons, segregated changing rooms and segregated wards based on everyone individually deciding if they are in Hufflepuff or Gryffindor.