I'm having a difficult time securing wins. Any help is appreciated!

OP GG - https://op.gg/lol/summoners/na/graise-0099

Hi! I'm having trouble winning my games and I'd really appreciate some help with what I can improve.

I've been playing with a self-reflective mindset the entire time and focusing on things that I could have done to close out a game orto make things swing more in our favor.

So far, I feel like these are my biggest problems:

-Farming too much

-Dying too much

-Playing either too passively, OR too aggressively

-Not contesting Dragon as often

-Not ganking as often

-Overall inconsistency

While these are things that should be easy to focus on, I'm having trouble applying these in the game. I try to play with the basic fundamentals of jungling but I feel like the chaotic nature of my elo makes these fundamentals hard to apply in games.

Not blaming anybody on my team, but rather myself for not finding and capitalizing on conditions that would help us win.

I've been playing a lot of Nocturne as of late, but I've been struggling with him a lot. With Assassin builds, I struggle with taking control of the map and getting us to win. I try to take advantage by picking off their squishy targets, but I find it difficult to achieve when a lot of them are consistently grouped.

For Bruiser Nocturne, I have more presence in fights and control overall, but I also lack the damage to help us achieve kills.

With all that in mind, I'm not sure what to focus on for improving, or how to focus on improving, especially in terms of adaptability. I'm also not sure if Nocturne is necessarily for me. I was wondering if a more late-game oriented champion with a safer engage or carry potential would be better for me? I was considering Amumu for a safer pick especially with team comps in mind, but I feel that relying on others do deal damage would make it difficult to win. I was also considering Graves or Viego.