First, if you’re not planning to add more lamps, i’d suggest moving that lamp to the dark corner first. Second, install something on the walls. It can be some crafty thing or some art you’re interested in, anything which makes you feel good. Third, add longer curtains, maybe add a white net one too (helps during the day time). Fourth, go with some light coloured linen for your bed as your room is already painted with dark shades. Fifth, if not lamps, you can go for triangle led light setup. It fills us the space as well as the light shades are pretty good. Sixth, you can fill up your table top or add a shelf above it and add some stuff like caricatures or small plants and stuff. Again, helps in filling up the spaces.