See this is part of the problem. A teenager who can't understand long-division thinks that it is all very clear and obvious, as things frequently are at that age. All well and good. But the thing about being young is... a lot of the actual issues with sex-based discrimination happen in teaspoonfuls or more as you age.
It took me quite a while and a lot of conversations to realize that my mother, grandmother, all my friends and relatives had ALL experienced sexual harassment, violence or rape and/or been massively penalized for being women. All the women in in your life who have been or will have been raped don't all turn up at once and tell you. You find out over time.
Before I got older and took up more space, I didn't realize how much a lot of men hate that. Now, I interrupt if I'm interrupted and talk over people who talk over me. I don't move out of the way automatically and I don't move my leg because someone wants my space. When I was a teenager, I was more self-conscious about that kind of thing.
When I was a teenager, I was policed for dressing: like a prostitute (thanks BF's dad), weird, being blonde and having breasts (pretty much asking for it, also clearly stupid), not happily enough (for not gurning constantly). Now it's being overweight, being older, still not smiling enough. After time you realize, 'oh it's the fucking patriarchy and there's no winning'.
Then I had a baby. And fuckity fuck does that make you realize your body doesn't belong to you.
I listened to older women, WoC, gay women, Aboriginal women, Muslin, Christian, Jewish and Wiccan women, women who have to work in the sex trade, women fleeing violence, women who are homeless, women who have gone through FGM. I found common ground in the hatred of us and the policing of our bodies.
And my outlook changed. I went from a choosy choice, liberal, man-placating 'feminist' to a woman who believes that there are wars still to be fought and they won't be won by being nice. They won't be won by centering men and they won't be won by people pretending that conforming to ridiculous gender stereotypes is liberating.
And don't call me cis.