The growth of her breasts and the coming of her “monthly visitor” are significant changes in a woman, but they are not the crowning moment of womanhood.
It’s not sex, any boy or girl can have sex foolishly, sloppily, mistakenly. Are there fifty year old girls? Yes, and 50 year old boys out number them three to one.
Where is the divining line of womanhood? It’s when they stand up and say “I’m the same as you; no less, no different. My worth is your worth and my rights are your rights; my destiny is my own to make.”
A woman is a woman when they accept who they are and stoically steer their own course.