Did all the levels and completed all the bonus objectives in each so where are the remaining levels? Is it worth worrying about or should I just move onto the desert?
They’re just adventurer levels (levels generally only available to pretesters), but I wouldn’t worry about them.
If you do want to find them, you can compare your levels to the levels here: https://codecombat.com/editor/campaign/dungeon
and you can access the map directly by using codecombat.com/play/level/name-of-level-here
where name-of-level-here is the name of the level separated by dashes.