Help on Build - Where to go next

First time on PoE's end game and I am struggling trying to determine what is the next best upgrade, or even telling if something is an upgrade or not from PoE.trade. I've been following 'Thunderous Applause' found here:

https://www.pathofexile.com/forum/view-thread/2218884

Loving it so far, not the fastest clear speed but very entertaining. Up to Tier 9(rares) on maps, no problem clearing that tier, havent tried 10 yet. Having a rough time sustaining maps though, can never seem to get enough to drop for me.

The biggest thing missing that I can see from the guide is an offhand with "Trigger a Socketed Spell when you use a skill" and high minion damage. Searching PoE I am having a hard time finding something that looks like a replacement for ~100 chaos or so. I dont know how the attack speed on my current offhand contributes to my overall dmg, replacements that I am finding dont have other offensive stats as far as I can tell that would make up for the loss in attack speed, unless the attack speed only applies to my offhand sockets skills which I only use to keep the Smite buff up.

Looking for any help, what a good offhand would be, improvements on the build, different gems on my passive tree, next best upgrade.