[D4] Hit a progress wall. Any ideas?

I've always been bad at minmaxing, playing games mainly for stories and escapism. With Diablo though the whole fun is in progression, gearing up, etc.

After completing pre-season campagin on a Sorc and a Necro, I decided to go with a Barbarian for Season 1.

All was fine and dandy until around now. I am at level 51. Content in Tier 1 and Tier 2 is pretty much a cakewalk. Content in Tier 3 is frustratingly hard. I have no idea how to gear up, as most stuff that drops for me in T2 is pretty low compared to what I painstakingly grinded through many many death-per-dungeon runs trying Tier 3.

I leveled using Hammer of the Ancients, but got bored of it and switched to Whirlwind (which I have fond memories of). Problem is, naturally in Fury management. Unless the area is absolutely packed with mobs, I don't seem to be able to sustain the whirlwind for long enough. On T2 it's OK. I do some fury generation then get back to it. On T3 by the time I get the bar filled again I'm usually dead.

Any idea what should I be doing? Is there some harder T2 stuff that rewards better gear? Or maybe easier T3 stuff?

At the moment if not careful I can die to even roaming elites in T3, while in T2 I can sleepwalk through pretty much everything I've seen...

HALP, PLZ <3