https://www.leagueofgraphs.com/summoner/performance/fiora/na/CritDozer
I use league of graphs to diagnose my problems. I was like silver 3 last season (albeit i didn't play more than like 15 ranked games).
Anyways you already have the answer kind of based off of your question. According to that league of graphs, most of your stuff is "below an average" silver Fiora. Specifically the metric you should look at thats below average is your "Kills + Assists". It looks like in the games you lost that you were extremely far ahead (like 11/0 or some shit), most of your kills were centered top lane and not so much in mid, and literally none in bot lane. While she isn't split pushing / while you have a huge lead, you should work your lead into some of your other lanes, forcing the enemy behind
https://matchhistory.na.leagueoflegends.com/en/#match-details/NA1/2759566022?tab=overview
When highlighting you, most of its top lane, a few mid lane, but nothing bot, who could've desperately used it.
Also your damage is significantly below average but I'm not sure if that's too much of a problem depends on how its build), it might even be fixed by some more roaming.
Anyways good luck on your climb my man.
. I figured she was a champion that could snowball very easily ( which i find is true ) and still be able to carry a team at times. However since ive been playing her that has happened maybe once. I find that im on a streak of doing good and team does bad, or I do bad and team does good. Im not sure what I can personally do to fix that.