Need Assistance (Recently Hit Diamond)

I recently hit Diamond and this is my first time being in it. I started to realize that after about 50 games, this was so much harder than Plat 1. I started to do really poorly and not winning my lane almost every game. I do main Yasuo, but that isn't the problem. After I started losing and worrying I would demote, I started to look up videos and guides and learning new things that would help me. I started watching streamers, and learning from them. I learned so much and have so much more knowledge in my head than when I did when I first hit Diamond. I realized though, that applying it was difficult. I started thinking before I did anything, but I can't seem to do anything with the knowledge I have. I think one thing, and my fingers do something else. Last game, I was playing Yasuo vs Riven top lane. I was thinking during the match up, and I got camped. My jungler came and i secured 3 kills in 8 minutes. I should 100% be snowballing now against a riven. Well, I know shyvana, their jungler, would attempt to camp me. After I took the first tower, I thought to myself "Oh, I should ward and see where I can apply my lead and help my team." I did the complete opposite, I stayed top, didn't ward, shyvana camped me, and I died 4 times. I then lost the game with a negative KD and didn't do anything to help my team. I am not afraid to say, we lost that game because of me. It seems that I'm losing tons of games because I can't seem to apply my thinking, I just do even after I think. I would really like help on how to stop this habit and do something else besides worry about demoting to Plat 1 again. I know I'm better than what I am playing, I just don't seem to be able to play like it.