Ice Strike Chayula Monk Mana Leech Questions

Hello monkes

I am playing Ice Strike Chayula Monk. Currently running Eternal Youth for life mana to ES, but I find with tougher bosses I run out of life flasks and im pretty much SOL. For ascendancy passives I am currently running Walking Dream, Lucid Dreaming, Reality Rending and Chayulas gift. Between the passive tree and gear I have 1.4k life 7.5K es and 1k mana. I was thinking of switching to Consuming Questions and Ravenous Doubts for mana leech.

I am not sure exactly where I can get mana leech. The only place I've seen so far is on the weapon where you can get some phys dmg to be mana leeched. I also see a couple of skill tree passives that boost that by 20/25%. I guess the question is if I get rid of Chayla's Gift and Reality Rending for the mana leech nodes and switch to CI losing the 1.5k life, but gaining Mana Leech to ES Leech, would it make me tankier against these end game bosses. The breech boss throwing hands gets me every time. I know I can also get some increased mana leech from jewels, but what is the main way of actually getting mana leech?

I'd appreciate any info!

Passive Tree Image

https://imgur.com/Z7LhQdK

Character Sheet

https://imgur.com/MmMrcvn

Doing some testing and need even more clarification lol

I bought a qstaff with phys damage mana leech and and took a few nodes to increase mana leech. So far this is what I found. It looks like I get about 14% of physical damage done as leech to mana and ES. So if my phys damage is 488-988 and I am leeching 14% that would mean I am getting back between 68-168 ES per hit. That doesn't seem too bad I guess, but I am still not sure if there are other sources of mana leech. Please let me know if my thinking is correct or if I fucked up somewhere along the lines

QStaff
https://imgur.com/XeqeUz7

Skill Gem Stats
https://imgur.com/HmQQE5Y


Ice Strike Skill Phys Damage Stats
https://imgur.com/114f0TJ