you know how gender is a spectrum right? well a demigirl is right in between a nonbinary person and a girl.
just like a demiboy is the same thing but between a nonbinary person and a boy

if you prefer staying cis, then you're cis! simple!
you might feel more comfortable to call yourself a demigirl perhaps...?

reasonable bruhing

it's ok to be nonbinary without using they/them, also do you feel connection to the female gender or you think you're something completely separated from male and female?

wait what is your birth gender