Ran out of quests

Tiny Death Star is a sandbox game, just like the original Tiny Tower. The addition of the questing system is there just to help you get started, like a hand holding exercise. If explains the game to you and gives you some startup cash.

The real content of the game is building your tiny death star up as high as you can make it, with really no limit. Your not out of content because your out of quests, since the original tiny tower had no quests and still had good staying power. The real gameplay is managing inventory, assigning bitizens and of course, adding levels.

Same thing happened to me with 9 levels. @Resorath is talking about the missions, which actually do continue. The Imperial quests are different. The missions teach you the game in the beginning and get you on the right track. They have ridiculously low rewards later in the game though. The imperial quests had quite substantial rewards towards the end. The only thing I can think is that they are going to add more in an update.

Yes, I have had the same issue. I don't think it's specifically a bug. But, there is a continued value to building the Imperial Levels, because many of them have unlock-able scene associated with them. So, at least there is that benefit.