Overall Grim Dawn is awesome but annoying quests and meager stash. The current annoyance is finding the sewer to get to the Malmouth whatever area. I’ve been around and around and I don’t see any sewer. I don’t like googling game solutions - it means the developers failed. There are many quests like this, ‘bring this thing to someone somewhere’ … does anyone enjoy run around and around huge maps looking for a NPC or a sewer or whatever?
Welcome to the forum. 
The game won’t hold your hand and direct you to quest locations. Read the quest log info and if really necessary check the wiki.
We will be getting more storage with the new Fangs of Asterkarn expansion.