Hi fiona!
As I read your posting, the first thing came to my mind is that you got outwitted by your dog. Sorry but it made me smile
She was just fine sleeping in the kitchen with the door closed but you have giving her more and more choices, which of course she liked better than sleeping in the kitchen away from the rest of the family.
What you can do is just put her back in the kitchen and ignore her during the night for a few nights. She will probably whine or even bark to get your attention but be consistent and never come to her.
At her age (6 months) she should be able to hold toilet for 7 hours or so. After you let her out just before you go to bed, she should be able to hold it until the morning comes. Once this becomes a routine, she will be just fine.
This can be said for everything else. If you don't want your dog to beg food, you should never ever feed even a piece of bread from the table. If you don't want your dog to get on the couch, don't let her on even once. (except for you have time and passion to train your dog to listen to your "get down" command - which my dogs do).
I think your dog will learn where to sleep fairly quickly. Good luck
