Gorgeous room, Missfood!
Lisagran just because a room is dark, doesn't always mean that painting it white is the answer.
Sioux have a range called (I think) Light & Space, which apparently are formulated to "bounce/amplify" any available light.
Think about how you use your sitting room, we don't generally go into ours until around 7pm, using the kitchen dining room during the day.
If you use yours in daytime then yes, you may feel that it needs to be as light as possible, but if not, then you could think about making it a bit more of a cosy, warm place.
Stark white can be harsh, what colours are using for floor covering, sofas, curtains etc?