https://poe.ninja/poe2/profile/KeeSe-5550/forbiddenrites/character/LittleGreenGremlingBud
Following buildguide from Ky but currently struggling a lot with T12+ maps. Maybe its my expectations that are a bit high I don't know, played very overpowered builds last two leagues so I'm kinda used to just facerolling through T15 on gear worth a few exalts.. or am I missing something big from the build? I know my gear is very bad but still.
Single target damage is the big thing that is lacking, bosses can take over a minute and I even run out of mana flasks.
It also looks to me like most damage upgrades will be very pricey, like trying to get up to 4 totems.. and getting a Split jewel is out of the question but that was kind of expected.

Am I missing something big or is this just how the build performs? In the guide it states it can do T16 at the earliest swap on lvl 70 with crappy gear but that is not what I'm seeing at all.
Should I switch to some other Gemling build, any suggestions? Anything but CoC Comet I guess.