Just replying here in case it's useful for anyone else. I figured out the problem, requiring me to roll a new toon.
Evidently, if you go straight to killing the main shaman in the sanctuary after only briefly getting the quest to do so, and you haven't learned the secrets, then after you kill her the other shamans like immediately complete the ceremony, killing all the refugees, and locking you out completely from the sanctuary. As a result, I lost access to all the quests and areas in the sanctuary, which meant that after exploring every square inch of the map and killing everything that moves, I was just shy of Level 5.
On my reroll last night, I fixed that mistake, and now am level 3 without having touched the remaining areas on the map. Meaning I'll have no problems reaching level 5 before mountain pass. Hopefully this is helpful to someone, as simply pointing out the list of available quests wasn't particularly helpful to me in this case
