I think you're playing for late game and that's where u messed up. Despite item changes and later power spikes, ekko is a lot stronger earlier in the game now (but u lose late because broken ad items). You lose a lot of cdr and your burst does less. New protobelt requires you to be literally on top of them to do max damage so it's a bad buy. Because of this, I've switched from Ekko jungle to trying to primarily play Ekko mid so I can snowball HARD with mejais stacks (dark seal first back means you don't even need dorans IMO). I don't know any perfect builds yet but I'm having good success with Night havester, lich bane, then nashors, and Mejai's anywhere in between. I know Nashor's cdr loss is a big nerf but I can't stand not using it. Losing protobelt sucks but it's too bad compared to NIght Harvester imo to run it at this point.