Help with Venom Gyre Deadeye Build

Hey,
I need help with my Venom Gyre build. My DPS on bosses is very weak and I die often. I know I have issues with chaos resistance, but I don't know how to fix it yet.

I tried playing with a shield today, but it seems like nothing changed except my DPS is down.

Also, is there any way to fix the mana issue? I'm running low on mana and have to run without flesh and stone.

https://pobb.in/6sXdReFvMI66

Any tips on improving the DPS and defense of this build?