Been doing several odd-jobs for the Companions but for some reason, the werewolf Totem (I am not cured) quest nor the purity quests will activate (I've completed the questline and have even done "Dragon Seekers" once).
What am I missing?

Try takig Aela as a follower and moving to another location say the underforge fire her the ask for work. *Only Aela gives Totem quests. If you see the lie "Is there any work to be done" instead of "I'm looking for work" it means a special quest like purity or totems of hicrine.

I'll try that, though that seems to be a strangely specific prerequisite. The guide, nor UESP, says anything about having to take her to the Underforge.

Its not a prerequisite but changing cells changes what job they were offering and Aela seemes to favor Totem quests while in the underforge. (at least thats my experience._