First of all, sorry for the dumb question…
It’s my first full playthrough of Grim Dawn, and I chose to side with Anasteria.
She gave me a bunch of quests, I completed them, and now can’t progress further.
From what I see here on gamepedia, the next quest (Black Heart of the Void) requires Respected status…
But how can I achieve this status if I can’t use the Bounty Board and can’t kill monsters to gain reputation? 
You get rep by killing Aetherials and Chtonics (heroes in particular) so do some grinds in plains of strife and necropolis and you will be fine.
Welcom to the forum btw
Thank you so much =) I didn’t know that Aetherials and Chtonics gave rep.
all factions have generic rep gains by killing a specific kind(s) of enemies
once you get access to mandates from all factions, those that you can buy and transfer to other chars, you will never have to do bounty again in your life 