The Sheltered Princess background is available yes but all backgrounds, besides the Pirate one, need of some choices to have been picked during the “character creator” for them to be available. For example, to unlock the Court Lady background you need to pick some politic related choices, to raise that stat.
The Sheltered Princes I think is actually the most difficult background to unlock because there are some choices that will completely lock you out of it if you pick them.
Here is a detailed guide on how to unlock each background (beware, spoilers!): 7KPP guide - Google Sheets (go to the Character Creation tab and check the Princess column, the choices marked as NEEDED are indispensable to unlock the background while those marked with a cross X will lock you out of it).
Btw, the thread is old but the game is still being on developement. Ally still posts from time to time on her Tumblr 