LoN Barber WD help

I can't even beat grift 90 with this build.

1. I know I should have the Barber equipped, but I have never gotten a good Barber.
2. For some reason, I seem to not do much damage to elites. It takes me longer than I should just to kill blue packs. Yellows I usually have to skip because I do so little damage. Then, I always run out of time, even if I get to the rift guardian with 4 minutes to spare.
3. I don't understand why I do so little damage to elites, even though white mobs are destroyed in seconds.

Am I doing something wrong?

My build: https://us.battle.net/d3/en/profile/H4YD3N-1519/hero/50468792