But every time anyone got up for a glass of water, woke up before her and went downstairs, whenever the boiler comes on, whenever the fridge/freezer do that weird defrosting thing they do, it'll wake her up. The kitchen is the noisiest room in the house at night really.

At the end of the day, it is her house, and I still believe she deserves a room of her own. I know it's annoying, I really do, (I used to hate sharing a room with my sister) but she's paying for the house. She decides what's happening I'm afraid. I'm not going to call you an Ah though. You can be annoyed that you were promised something you didn't get, and you've found a solution by sleeping on the sofa.