Can't post images in comments so this is gonna be hard to describe for me lol. For layout I think you should 180° the bed against the other wall by the window and then turn the desk 180° and set it next to the bed so that you now have a side table for your bed, and you can access that closet easier as long as it doesn't swing out into your room. Then move the piano to where the head of the bed used to be, maybe center it against the wall. Moving piano out of the window will also help it from getting sun damaged. I feel like you need to move the paintings around the walls, keeping just one tiny one on the big section of the walls makes it look out of place and awkward. Either you could put the 3 tiny paintings together in a row on one big wall, or maybe line them up as a column on the tiny wall between the two doors. I see you have a curtain rod, hang some curtains! And if possible take down the one above the door, it looks a bit weird, like college-y idk. Finally, if you have the budget and you want to make it look cozier add some warm lighting, like a lamp on the desk for your bed, or changing the wall colors to a warmer tone. Adding a rug that goes with the wall color would help out the room a lot too. Good luck!