What gender should my main charecters be?

My charecter is currently a girl. But, I originally wanted to leave the gender ambiguous. Now, I want a solid answer. I made a 民意调查 of this, just ignore it. The charecters name is Bentley, and I don't know if the plot really applies to what their gender would be, so I'm not gonna explain it. But here are the options:
-Male
-Female
-Transgender (male into female)
-Transgender (female into male)
-Agender
-Bi-gender (being both male and female at the same time, 或者 feeling 更多 like one at one time, and the other at another. I personally identify as bi-gender.)
-Any other gender that I have not listed. Feel free to tell me then!
Also, keep in mind the definition of gender. Ones gender identity and their actual body are different. Gender is how 你 feel, and how 你 identify mentally.
So if Bentley we're to be a bigender, such as myself, they would not have male and female body parts, but instead a male and female mentality.
Thanks to anyone and everyone who helps! Much appreciated! Sorry for such a long description, but once again, thanks!