Please stop play Riven, she is a really difficult champion to master and she is really not good for low elo.
Your farm is really bad. You had a Ziggs support game where you had 50 CS (don't steal your adc/laners farm btw) and then a Fiora game where you had only 67 Farm at 22 Minutes. You should have atleast double the amount of that. Especially with Fiora, a champion that has to scale and therefor needs large amounts of money.
You die way too often. Atm you have an average of 7-8 deaths (often already around 20 Minutes) some games you even have more than 10 in under 30 Minutes. Reduce this to not more than 5 Deaths in a whole game. You can't win lane? Stay under tower or go roaming, trying to fight in lane and feeding your ass off helps no one.
Your mechanics can't be this good if you have a negative winrate. Watch professional plays and look how people play her, try to understand WHY they do certain things and not only how.
Diana is not that hard to play, but if you ever look for a new champ always go for the easier ones like Annie until you can play without problems on Gold/Plat Elo. Then you can try your hands on the harder ones like Riven.