Infertility, voluntarily childlessness, inability to breastfeed or being pre or post menopausal doesn't make you less female, no of course not but menstruation, childbirth and breast feeding happen because you are a woman, that is the female reproductive contribution. The sole reason any of us exist. So it is a non sequitur to suggest otherwise.
Whilst you can say having children is not a condition of being a woman, producing milk and giving birth are a condition of childbirth, and only women give birth.
We are embodied.
Our bodies are either male or female.
Until the 1960s and reliable contraception, having children was a condition of having sex and not being infertile).
Having sex then wasn't always a choice. Having sex now isn't always a choice. If I choose to have a child I have to accept I will give birth and produce milk. I don't exactly choose to do those things, the choice i make is to have a child or to have sex or to use the milk I produce.