help nidalee tips

so ive been playing nidalee for quite a while now im not a fantastic player but i have carried some games and im alright with landing spears i gues ofcourse everyone has its bad games and since im a beginner id be unsure if my good games r me being good or my enemys being bad

annyway im playing nidalee as an ap jungler wich works fine for me even if my entire team is losing id might turn the tides in some part of the game by spearing the entire enemy and making them back or go into the teamfight on half hp

how ever i noticed that unles im INCREDIBLY fed theres no way to deal with some champions unles they have been hardcore bullied the entire game basicly most tanks... nidalee cant do much against them since i play as a jungler what id usualy do is try and get my adc fed so hed be able to handle the tank, if the adc is a total noob wel than there doesnt seem to be much i can do but hope for my team and 2/3v1 him but this al stil seems fair cause this tank wil stil go down

how ever a not so fed riven/fiora seems to be imposible to kil no mather what id do ? if theyr at 20% of their hp a spear stil doesnt seem to kil them and jumping in afther hitting the spear just gets me killed ive been in situations where fiora wasnt really fed and wed cought her alone 3v1ing her and she simply kils us 1 by 1 ? i feel like this is kind of unfair ?

i gues id understand how a counter pick is supose to crush the other player like heimi > yasuo or zilean > xerath but if 2/3 players show up there supose to win arent they ?

how are you supose to deal with this ? can annyone help me ?

my grammar sucks english isnt my first language and im dyslectic get over it :p