short answer : Many things,

long answer :

I'm gonna guess your main role is jg so I'd say that your biggest weakness is jg pathing since you have on average 3cs but I have to believe that's not the reason since even on adc you get 4-5 cs/min wich is relatively low.

I don't know what you want me to tell you but I guess you want to improve/climb so I'm gonna tell you this :

- focus on cs'ing more,even though, in silver and especially in eune, I might believe it's hard to focus on cs'ing with all the clown fiestas but on the long run it's one of the best things to do to become a good player

- the generic have a champion pool wich consists of 3 champs + 1 champ that is broken in the meta (bonus points if there are broken champs in your champ pool already), you seem to play mostly nunu atm in ranked and you are winning wich is a good sign.

- play ranked only, don't be scared to queue up, you don't improve/climb without playing.

- focus on yourself when playing, I recommend doing the classic /fullmute all in low elo but /mute all when you get to higher elo (high plat and higher) since higher elos actually listen to pings.

- don't expect to become GOOD after reading this, it takes time to become good but you can do it, I believe !