[Lightning arrow/ Blast rain]Help, I need suggestions to make my character better !!

I based my build on Neversink's beginner tornado shot guide, but right now I'm kinda stuck at a "meh" level of dps : I can't even one shot tier 1 map bosses.

I need suggestions item wise. I'm planning to swap my current weapon to a Doomfletch's prism when I get it to a 5L or 6L



Here's my current skill tree

Here's my optimal final skill tree