The following is all level 5 and 6 quests. Check your "Finish" quest log by hitting the J key and see which one you're missing.
The one people miss the most of the level 6 quests is the Travel to the Communication Tower one (called Boosting the Signal). Make sure you've auto-routed to this location before returning to Enocia.
If you havent done any level 6 quest yet, the first one you have is to talk to Guard-Captain, Carl. He's located in Enocia at 10915, 10234. You can see "Carl" on this map
towards the name near Davidson.