I have basically completed the game. Great game, btw!
My question revolves around the secondary blueprints that are unlocked by accepting a quest approximately mid-way through the game (gypsy or foreigner). I had set the game aside for some time and must have forgotten about this particular quest. When I picked it back up, I started down the main quest line again and was able to complete the castle, etc. Now there are no active quests and I cannot talk to the queen anymore. I am pretty confident I have built all the buildings because I was able to complete the castle and every other building in the lower-half of the blueprint sheet.
Those buildings are mutually exclusive. If you've got the castle and there are no more quests, then you've reached the end! Earlier in the story, you can pick either the gypsy path or the merchant path, but not both. The only way to see those buildings is to play through again (or start from an earlier save) and take a different path.