@Nightinghawk:
"I have to argue on the concept of feminism only for "biological women," since I feel that creates exclusion and, depending on the definitions or views loaded in the term, would exclude people who have lived as women their entire life."
Why is exclusion a bad thing, though? Take Black Lives Matter - it is particularly focused on the oppression of black people. It is a civil rights movement that is exclusionary to white people (hence the dismissal of 'all lives matter'.) Any attempt to widen the bandwidth of the movement to encompass white people and white concerns is rightly rejected. So why must feminism include everyone? Why do women not get their own civil rights movement? I could live as any number of things my entire life and that doesn't actually make me that thing (as Rachel Dolezal, or Hilaria Baldwin recently discovered.)
"I've seen a lot of GC people say that "biological" relates to body parts, reproductive organs, chromosomes, facial features, and I personally find that incredibly reductive for the concept of women."
In philosophy, 'reduction' is when a concept is nothing more than x. It is entirely explicable in relation to x. So, for instance, water is nothing more than H20. Once you grasp the properties and nature of H20 you have learned everything relevant about the concept of water. When we say that women are female, and female is a biological concept, we aren't reducing women to just their biology. Women are not 'nothing more' than their biological sex, because they are also people.
To paraphrase Jane Claire Jones, here, saying a woman is biologically female is NOT the same thing as saying her entire essence or existence is nothing but her femaleness. She is a person and a human being. Jones theorises that we still find it difficult to believe that females are fully human being, which is why some people think there is some kind of contradiction in saying that people can also be female. I would also ask at this point, what a 'non reductive' definition of the concept of woman looks like.
"Relating feminism to strict biological categories but also against the oppression of female reproduction seems somewhat counterintuitive to me (though there is truth in women being oppressed due to biological differences), since it appears (in my understanding of it) to relegate women to mere bodily functions rather than expand women beyond the patriarchal expectations constructed around those bodily functions."
I don't see how it is counterintuitive to be against the oppression of female reproduction while also saying that women are biological females. Women's female sex explains their oppression. Their sex is why they are oppressed. Feminism aims to liberate the female sex from oppression. The ultimate aim is to have no female human being oppressed on the basis of their sex.
Saying the definition of woman is an adult human female does not relegate woman to mere bodily functions. That is quite a sexist way of thinking, to be honest. Women are people, full human beings, who also happen to be female. This is like saying that disabled people are nothing more than their disability!
I would also note that if you expand the concept of woman so that it is wide enough to also encompass women's oppressors, men, then something surely has gone wrong.