She's a woman. Simple as that.
Chromosomes are far from simple. Some are, yes, XX or XY. But others are polysomal or monosomal or some complex mix. It's far from unknown for women to have XY chromosomes, for example, where they've carried a male child and unborn boys XY chromosomes are passed back to the mother through the umbilicus.
Biological sex is not so binary as most people seem to think, in general.
As for gender, well that's simply a case of the person stating who they are. There's no test for it. None. For myself I'm a woman. I have female breasts. I have smooth skin that's more sensitive than men's. Having not yet had surgery (soon!), such as Corey did, I still have a penis, but I don't have erections. And I'd grow a beard if I didn't take steps to prevent it.
None of this makes me any less a woman. I've lived as a woman for some time now, although I didn't come to terms with my womanhood until I was 48! My legal name is Abigail. My official documents list me as female. My medicals records say female, so I'm invited for regular mammograms. I can count on one hand the people who knew me prior to transition. I don't own a stitch of male clothing. I get catcalled and whistled at (even at the age of 50!) - men lose their minds at the sight of a mini skirt and heels. I get talked over and my expertise is dismissed. And my constructive ideas are frequently stolen.
Etc etc etc
But really it all boils down to self-determination. Corey, in her piece, told you she's a woman. I'm telling you here I'm a woman. That's it. It's not confusing. It's not deceptive. It's not a matter for debate, suspicion, or accusation.
We're women. Yes, we're trans women. But look at it this way... Speaking for myself, I'm a tall-ish woman. I'm an intelligent woman. I'm a creative woman. I'm a woman who rides motorcycles. I'm a woman who writes for a living. I'm a lesbian woman. So, along with trans and many other adjectives, those are the type of woman I am. But ultimately a woman is what I am. Whatever else you might think of me, that I'm a woman, that Corey is a woman, are very simple statements of fact.