Penance Brand Elementalist　build help!

I'm new to PoE and am following this build, but I'm not getting very strong even with the same gear. I can crush trash mobs in T16 maps, but bosses take a really long time to kill.

92lv https://pobb.in/HL3-18mP2iq_

100lv https://pobb.in/j1w3cDhnzBts

Here is my build. What changes should I make to make it stronger? Also, please let me know what I should buy next.

https://poe.ninja/poe1/profile/ggxd-8563/allflame/character/ggxdgg

I am using a translation tool, so I apologize if anything sounds odd.