HELP ME WITH FIORA WHY CANT I SOLO CARRY WITH HER

Legit this is soooo fucking annoying. Ive had multiple games recently where I snowball with Fiora and manage to fuck up the enemy team. I was handling 3v1s no problem, but I can never EVER solo carry with Fiora, and I have absolutely ZERO idea as to why I can't. What in the fuck am I doing wrong? I know she's a duelist who prioritizes 1v1's and 1v2's and possibly 1v3's, so I split push, and I draw their attention towards me and while I do that, and deal with the 2 degenerates that want to 1v2 Fiora, my team SHOULD BE forcing a 4v3 fight bc they win 9/10 times (emphasize "should be", because they don't force the fight most of the time).

BUT FOR SOME REASON idfk why but I can never capitalize by doing this, or my team needs me to help them because they don't know how to stall out under tower and let me finish my split pushing, so I try to go help them, but we completely throw the game away by doing this.

As Fiora, should I LEGIT splitpush the entire game? Should I just say "fuck u team" and not help them at all and prioritize my split pushing capabilities? This seems like the way to go, but I always hear "be there for your team and you will win more games" so I'm not really too sure what to do, especially if it's getting drastically late in the game and the enemy Twitch becomes the hyper carry.

Just someone help me out here. I dont know why I cant solo carry with Fiora and if I dont find a reason I'mm probably end up losing my mind.