LF gearing advice

Hello. I've been following this build.

https://www.pathofexile.com/forum/view-thread/2275623

I'm a bit stuck as at around t10 maps and I'm not sure how to go higher. I've got some decent items. Not perfect rolls but not so bad I feel like any single one is a bottleneck. I could get better rolled items but I'm going to get what? 100-200 hp? at t12+ map bosses and syndicate get extremely rippy and a lot of things straight up 1 shot. Can you please give me some examples of items that would give me a significant boost? As it is I'm farming and buying items with better rolls for marginal gains and I have no idea how to safely farm higher content.

EDIT: path of building: https://pastebin.com/TDkSK7vj