How to figure out where in a questline I am?
Solution 1:
I've managed to solve my problem using two resources - first, an addon called Quest Completionist. It provides a very intuitive interface into my quest history - much more so than Carbonite, even if it has far fewer features. Second, I just look up the quest lines on Wowhead and search in there for the quests. Using a binary search I was able to quickly find the first quest in the chain I had not completed. I used this in multiple chains and the process was fairly smooth.