White paint will look duller than anything as it even though it will look lighter the lack of light will make it depressing. Better to go with a mid tone colour. Try a stone colour and add some dark and light accents.

Are you using Silk Emulsion? Any matt paint will look dull, especially in a 'lack of light' room. If you are having real problems, then you could also try on a feature wall a pale blue, pale grey or pale stone metallic, with white silk emulsion everywhere else. Ralph Lauren do a good range, but there are other equally good makes, just google Ralph Lauren Metallic Paint

Avoid cold colours, like blues, unless they range to very light turquoise, that can feel calm. Or look to the warmer, hotter colours, but as pale shades, nothing too saturated. Be aware of the psychology of colours. Strong yellows can make some people feel agitated. I have used a soft bamboo (very light soft stony yellow-cream. It is used on the north side of the house and always looks great.

If there's a lack of natural light, the room will never look light and airy. Better to steer into the skid and embrace it for what it is. Pick a deep, moody hue and make it really cosy and sumptuous then enhance it with beautiful lighting like some gorgeous lamps. Playing with the contrast between light and shadow will make the light you do have more noticeable and allows it to be appreciated.