Choose the gender you feel comfortable with. I’m getting all of the definitions from Wikipedia. Also, when you choose a gender identity, it’s not set in stone.
Agender - It means that you don’t have a gender.
Bigender/Bi-gender/Dual gender - It means that you have 2 genders.
Trigender - It means that you have 3 genders.
Demigender - It means that you partially identify with 1 gender and another at the same time.
Demiflux - It means that the stable part of yourself is non-binary.
Genderfluid - It means that you’re flexible about your gender.
Transfeminine/Transmasculine - A transfeminine person was born male and mainly has a female gender. A transmasculine person was born female and mainly has a male gender.
Pangender/Polygender/Omnigender - It means that you have multiple genders. You might also identify as every gender at the same time.
Xenogender - It means that your gender is an animal, plant, things, etc.