Champion pool revamp

I switched to jungle main after burning out on heimer and I recently hit gold IV and am struggling w/ my champ pool. I love nunu but my last few games have been pretty weak w/ him, missing out on early kills when I gank, and not being able to keep up w/ objective control enough to make up for lacking the influence of the enemy jungle (especially when I'm missing my early ganks in match ups that I don't win if I show up to counter gank). It extends to basically struggling a bit with some of the utility and tank play that I like in top/jungle, and having some success w/ higher damage tanks like shyvana by farming fast and stopping the enemy jg influence by bringing lots of early damage in counter ganks to prevent my lanes being bullied or dying.

Especially w/ the new mundo buff I'm curious about trying to shift my champion pool to include some more damage in my champion pool rather than primarily utility tanks, or if I should try to improve my early influence and objective control w/ the champs I've been playing? I think so far I've been winning w/ utility tanks bc players couldn't punish early leads hard enough and I could come back hard in mid game and team fights, but as I climb teams are better at not giving back leads (still not great but more often they don't throw) and I do better w/ early influence on stuff I can fight early w/.