You are in the middle of dragonspyre! You will know you are at the end of Dragonspyre once you are on the Dragon Staff quest area. If I'm wrong I'm terribly sorry, I haven't been playing in Dragonspyre...For quite a while...But remember once you get the quest to ride a dragon your so close to Malistaire!!
Keep it up! You are HALFWAY there, still need one dungeon (Labyrinth) then the whole of DS Academy, The Forum, and then the dungeon EVERYONE is waiting for, The Great Spyre, where you battle Malistaire! :)