KawaiiSuika - I'm always willing to learn so please inform me of my incorrectness (this sounds like sarcasm but its not). I'll admit I may be ignorant and spout cap but I am willing to be informed if I am wrong.
I noticed a couple of things off the top of my head:
1) Gender and sex are not interchangeable terms when you're talking about gender identity even though they are often used as such in other contexts. When people talk about their gender in the context of identity physical sex markers don't really enter into it it's a matter of psychology. Your gender identity is unconnected to your biological sex characteristics and a trans woman who has not transitioned at all is just as much of a woman as one who passes perfectly as cis. You could theoretically make the argument that trans people are still biologically their assigned sex/gender but it's super dismissive and rude and you should not ever do that because it's just cruel pedantry for the sake of being a jerk.
2) There are more than 2 sexes. Intersex people exist and their sex characteristics span the gamut of what we traditionally consider "male" and "female." There are also more than 2 genders as the gender binary is a social construct predicated on the assumption that there are only 2 sexes.