

I don’t disagree with you that society does think that way, but I disagree with the sentiment so much.
I’m 33 and afab. I accepted being called a “girl” until I was about 23 (probably not a coincidence that that was the age at which I graduated college), but it started chafing at like 16, even though I didn’t have a good alternative at the time (because I agree that “female” as a noun feels gross). If someone called me a girl now I would correct them without hesitation in basically every scenario outside of a eulogy or wedding speech.
I really wish there was a better option. I don’t really like “woman,” but it’s better than gal, lady, dudette, chick, or girl imo. I’m perfectly fine with guy or dude, especially in plural, but I’m probably an egg, so that colors my perspective for the singular use a little.
It’s also not an exact science, especially if you’re not on hormonal birth control. My cycle is 27-29 days, unless I’m stressed, in which case it can be up to 40 days. My period then lasts 3-4 days, but every 7-8 months, it instead lasts a full week and is way, way heavier and more painful than normal. No medical issues that my doctor can tell, sometimes it just be like that. So I will know that I should be getting my period in the next couple of days, but it’s never exact.
I used to be better about tracking it, but I realized I could feel a twinge about 20 minutes before the bleeding starts. Now I’ll even wake up to it, so there’s really not a downside to not tracking my period. (Except unforeseen medical issues, bc failures, and general bodily awareness)