Agender
Having no gender, rather than a gender that sits between others.
An agender person doesn't experience having a gender. Not a small amount, not a mixture — an absence. Some describe it as gender simply not being one of the dimensions they exist along.
It's worth separating this from androgyny, which is about presentation, and from being non-binary in the broader sense, which can mean having a gender that isn't binary rather than having none.
Agender people use every kind of pronoun and present in every kind of way. The word describes an internal absence, not an outward style.