Whirlwind build definitely isn’t particularly good for leveling, unfortunately. To be most effective, you really need access to the paragon board + a few pieces of gear/aspects. I’m following this guide, so you can keep a look out at least:
https://maxroll.gg/d4/build-guides/whirlwind-barbarian-guide
I switched to spin2win after level 50 and never looked back. I know it isn’t as strong has HotA builds in the long run, but it’s just so satisfying when you get your cooldowns reduced enough to tear through packs. Currently lvl 72 and having a blast slowly working my way up the nightmare dungeon ladder (most recently ran a 30).
That was me for most of my playtime so far, and then BOOM! Two nightmare dungeons in a row he showed up and wrecked my shit before I could even get going.
Whirlwind is rough without either the Bold Chieftan’s aspect or the Marshal Glyph’s secondary effect. Both is obviously preferred, but at least one is almost essential to make the build function in higher tiers. I waited to even attempt switching over to WW until I had enough paragon levels for a fully-powered Marshal Glyph, and it helped a lot.