So, since you are so wise in the ways of womanhood, consider the edge cases. Is someone who has had a hysterectomy still a woman? Is someone born with intersex genitalia a woman? If they were assigned female at birth? If they weren't but have the XY chromosome? What about someone who has an XY chromosome but is insensitive to feminizing hormones, and so fails to develop any female secondary sexual characteristics?
The things that make us what we are are tremendously complicated, even (or especially) on the biological level. It is not always as simple as looking at the chromosomes. I'm not (unlike some people on the right) DECLARING that any particular people are women; I'm just not willing to kick them out of womanhood if they themselves tell me they're women. Big tent; listening, not prescribing; individual self-determination: I feel that those are the virtues I'd like to cultivate and to see around me.