"Cis" is "not trans".
"Transgender" is having a gender identity that doesn't match your sex, yet no-one will say which sexes (physical body) match which gender identities (feelings). So you might assume that "woman" matches "female" but then told it's wrong to say that women are female.
"Agender" which as far as I can tell is "not having a gender identity" comes under the trans umbrella.
So to be cis you actively have to have a gender identity that "matches" your sex. Which I'm fairly sure I don't. I always thought woman was synonymous with female adult, so I've always thought I was a woman, because i know what sex I am. But apparently it is wrong to say that that is what a woman is. I'll know if I identify as one when it's defined, which it never is. Until then I'm stuck with the same English language definition I, and most other people in my culture, have grown up with.
Either there is something female about being a woman, or there isn't, in which case what are TW identifying as? Surely not a bunch of ridiculous stereotypes about how female people are presumed to think, act, feel etc purely because they are XX?