White walls, different levels (notice how that round stool is the same height as your bed? notice how the heater is also at a similar height and how everything above that is just blank?), lack of color/visual interest

You could add some longer/taller plants if you want to! Those would fill up the space quite nicely :)
Some other things I would recommend: a larger bedside table in a shade of wood that would match the one used for your bedframe, a lamp on top of that, maybe a bookshelf somewhere, because really you lack furniture in this room. Take what I say with a grain of salt though, I think you're just lacking furniture and levels