This is a fascinating discussion. Please excuse the long post: what I have read has led me furiously to think, and there are concepts familiar to others here that are new to me, so I'm bursting with thoughts.
I so much identify with Beachcomber's phrase radicalised by motherhood. I was entirely focussed on my profession until I gained a little DSD. We had her 2.5 days a week, and what I learnt from her and about my DH changed me more completely than I would ever have believed possible. Luckily, though we'd agreed we wouldn't have kids, my DH was totally laid back about my about-face.
I'd never experienced serious disadvantage as female until I became a mother. The mild denigration and sexual harassment I'd had before was nothing compared to this. In my workplace mothers had the lowest of all positions, regardless of job title. A mother = unreliable, not committed to her work, unpromotable, a liability. I was bullied and sidelined, by my male boss but also by other women. It ended with a 3 day discrimination case funded by my union.
Pregnancy and childbirth were pivotal experiences. There's so much I could say about its effects on my sense of self. Before I had a baby my body was whole and solid, like an apple. Afterwards I felt more like a crumpet or a stew. Everything leaked: blood, milk, tears. Due to my specific obstetric issues, my vagina was unaffected but my belly was seriously damaged, the muscles cut and sewn up badly, and a vertebrae mashed. My body was damaged and left open, or that's how it felt. The process was irrevocable, universal.
But my biggest feeling about the whole experience, and of motherhood generally, has been awe. Awe at the everyday miracle of reproduction, and the massive undercurrents of biology and instinct that move silently within my body and my brain. Like Garlicblocks, I was a young adult during the late 70s, early 80s, when it was fashionable to transcend gender, experiment with both/all constructs, and so on. Having babies blew that out of the water for me.
My body amazes me. My periods arrived between 11 and 12am every fourth Saturday. I loved that -- that my body was as methodical as the moon. Even conception was powered by my subconscious. My younger brother and his wife had their first baby on 13th February, I gave birth to mine on 13th November. OK, we were trying for a baby, but talk about sibling rivalry! I visited the hospital, admired their baby, went straight home and started ours.
What I'm trying to say is that, at least in my life, being female has been very precious to me, perhaps partly because as a young woman I rejected the assumptions completely. But, as it turns out, most of what matters most to me is to do with being female. I can't agree with LRDtheFeministDragon's idea that the distinction between people with penises and people with vaginas doesn't matter. It does. Having a vagina has been pivotal to my life. It's also central to my sexuality, which is very genital focussed.
It's very clear to me that in previous generations, before contraception and modern medicine, before washing machines and freezers, having small children disabled most women from any participation in life outside the home. That's where the oppression comes in, in my view. Because women have so frequently been dependent because of repeated childbirth men have taken advantage of their relative autonomy to control and dominate us.
The patriarchy, when benevolent, sees the position as being that mothers usually need a provider, and, as the saying goes "He who pays the piper calls the tune." Whoever brings home the bread is boss. When hostile, it sees us as bloody useless sheep, objects who breed, useful for that and for sex, but not much use at anything else.
I think sex matters, male and female, but that's not the same as "womanhood". I am no more typical of that role than any other person. I've had serious problems because I don't live up to local ideas of feminine. That's a story all by itself. My DH and swapped roles, which wasn't an issue while he was alive, because between us we got it all done. After he died, all of a sudden games kits were forgotten, dental appointments missed. I might have an impressive CV but I was a failure as a housewife. My bereavement counsellor suggested it might help to think of myself as a man whose wife had died, and to offer this idea to others. It helped a bit, and fitted very well, but I was still the focus of intense disapproval for not living up to the neat, floral stereotype of Surrey housewifery. I was very surprised by this.
"Femininity" - womanhood - is whatever your particular culture defines as how women should be, and being female is your body, and parts of your brain (most of which seems to be subconscious). Gender is a construct, but the idea that sex is also a construct seems preposterous. It makes no more sense than saying being a mammal is a construct.