There are only 2 genders

At least I believe that to be true.

My school is known in my city for being very gay. We have our own pride parade, gender neutral washrooms and rainbow signs everywhere. I'm not really into that scene anymore. I used to be super involved in grade 9 when I went through a veeery cringe "bisexual phase." Ugh...

I totally believe that homosexuality is valid, I think it's a spectrum and the only true sexualities are straight, bisexual and homosexual. Ah, and aromatnic/asexual, since I am aromantic myself.
But pansexual, demisexual and others? Nah, I think that's fluffy bullshit.

The whole gender thing is where I tend to recoil. To be completely honest, I don't like the transgender identity, but it's not hurting anyone nor does it effect me so I support it 100%. Even if it is a "mental illness" if transitioning cures that mental illness then encourage tans people to do just that and give them rights (but don't let kids start to transition until they're 18).
But I completely disagree with non binary, gender fluidity or any genderless/genderful identities. No way, you cannot be both or none. And I am not going to refer to anyone as "they/them." If you have a dick, you're a guy and if you have a vagina you're a girl, unless you're trans then you're the opposite. Gender is not a spectrum, it's male or female.
And if someone identifies as non binary, why on earth can't they just use the bathroom of their biological sex? Why does my school have to take space out of the library to convert to a gender neutral washroom when we have 5 pairs of gendered washrooms already?

"Bah humbug" - me as the rest of my school's student body rejoices in front of the gender neutral washrooms.

In addition, there's legal problems that arise from making gender "non binary." It just fucks up the system/society, and makes no evolutionary or biological sense.
There was a girl in one of my classes last year who identified as non-binary and had all the teachers refer to her as "they/them." If I was a teacher I would get really irritated really quickly. She looked like a girl, she dressed like a girl and she talked like a girl. Watching her correct poor substitute teachers to call her "they" was just plain irritating.