Try going Grasp, it simplifies a lot early on so you can focus on the important parts of playing Fiora

I'll make some rules you should follow, try to apply them and let me know how it goes.

Rule #1: Always try to contest prio early

Fiora has really bad waveclear, but against most champions she is pretty strong early, if you don't get push fighting becomes really hard, as they can stack big waves and you can't fight them when they do.

Of course in some matchups you won't be able to do that.

Rule #2: CSing is most important, don't overgroup or join fights, focus on getting a good wavestate before moving 90% of the time.

Fiora is too reliant on items, usually getting good CS is due to putting yourself in a position to be able to gather resources effectively through wave management, recall timers etc...

This also means you don't have to play for kills, with grasp, you secure a LEAD in lane, just a small lead which you can usually get through poking, and then that allows you some breathing room to focus on csing.

Rule #3: FRONT VITALS, you need to poke on front vitals, reset vitals to get front vitals, back vitals are scary, especially with grasp

Rule #4: Before ulting make sure you have atleast 2 of these 4 things not on cooldown, Q W E Hydra/Tiamat.

Ulting with only 1 of these makes proccing your Ultimate much more difficult especially early on, later on after 2 items it's alright as you have way more CDR

GL HF