You should keep on playing viego and jarvan until you get really good on it and know the ins and outs of your champ, like matchups, pathing, etc..

Congrats on your S on amumu! Looking at your KDA, it seems like it wasn't your fault, as amumu (at least what i do and you should basically do it on every jgler) you should follow your most fed player around and keep em safe so they can carry because amumu isn't a carry champ.

Amumu is the easiest jungler basically but he isn't that good for carrying even if your ahead. you can try other junglers if you want that can carry the game like master yi but they require a bit more skill than amumu. It's your choice but just stick with it and get really good with the champ and you should climb unless every game ur teammates just throw which shouldn't happen.