I'm already 12 and I would like to play fortnite. My mother doesn't want that because she's a teacher and you know that every child in school only talks about Fortnite. I'm also excluded from my class just because I don't play it.
I think it won't be easy to convince your mother and I don't really have any tips, but I can tell you how it was with me. When fortnite had this incredible hype and everyone gambled it, I was relatively little interested and I was not excluded. I then watched the game in Chapter 2, Season 1, had 4 seasons of fun for a long time, collected 650 hours of play, then Season 5 was really dirty and was no longer fun, and Season 6, which I played once (2nd round) was really a complete total crash.
I myself play more Nintendo games and many simulators on the PC because I enjoy them and the community in various online games is not so terribly toxic. That means I don't play CoD, Rainbow or other stuff, today I can have a say in the breaks when the topic becomes 0, which doesn't particularly bother me. I go to a few girls from my class who talk a bit rubbish and is good. (It was the same with brawlstars etc, I wasn't interested in anything and just because a game is in the hype I don't have to be so boring and play it too)
I'm also often seen as an alman or not a real gamer because I don't really play shooter games (except for PUBG), or because of the simulators I'm often Bernhard, but that's more like a little among friends. Because firstly I'm Pole, secondly I gamble for 8 hours or much longer in a row, and also chat with people and gamble with them if necessary.
End of the song, listen to mom, she only means well and I don't know if your friends are real friends if they seriously exclude you, but you have to consider that you are in the 4th, 5th, or 6th grade. It usually works like that, unfortunately.