At the risk of getting on the bad side of Kiwi Farms, I'll provide some backup OP.
It's pretty simple, schoolgirl uniforms represent youth and fertility. And that is what heterosexual males, when they're not virtue-signalling from the left or right, like. The schoolgirl uniform, let's call it a fetish, is probably the most vanilla fetish. From most degenerate to least degenerate:
Top tier: zoophilia, necrophilia, etc
(every other fetish)
Low tier: Schoolgirl uniform
Bottom tier: Missionary position
I think school uniforms are culturally intrisicly linked with youth. A 50 year old woman wearing a school uniform looks about as weird as a biological male wearing a skirt. Which brings me to the next point:
Where my theory breaks down is that the sexy schoolgirl thing is popular in America too, where school uniforms are far from standard. But I've seen movies and tv shows where teenage guys in regular schools are lusting after girls in private Catholic schools specifically because of the uniform. Could that be it? How common are these private schools with school uniforms in America?
While America is an exception when it comes to compulsory school uniforms, one thing remains constant: biology. Remember what I said about youth and fertility? Most porn site studies show that "teens" (or some variant of it) is the most popular search term, regardless of age or country. That was before they got cucked and removed it as a search term from future studies. No different than the FBI omitting race from crime statistics.
But as you said, despite the absence of school uniforms, America has cheerleader uniforms which serve a similar role and this is reflected in their culture via movies etc. Even Japan made a video game called Lollipop Chainsaw with a blond girl in a cheerleader costume as the main character showing that some things can cross cultural barriers.
Speaking of Japan, they are obviously known for the schoolgirl aesthetic as both a sexual fetish and as a form of fashion. I think what makes Japan different is that they are more honest about what they like. The fact that you feel shame for having this fetish reflects the culture you live in and the entities that influence your thinking. In other words, a combination of Christian prudishness (no sex before marriage, sex for procreational purposes only etc) and Feminist prudishness (you're a pedo if you find 17 year, 364 day girls attractive, etc). Both of which are absent or near-nonexistent in Japan.
I respect women and think they have agency so I should point out that women also use their freedom to make the choice to put on a school uniform, knowing it attracts eyeballs and attention.
Anyway, I don't you but apparently you're on meds so this whole school uniform thing is probably the least of your problems. Maybe look into that. And get more sleep.