Hellobee Boards

What about going ahead and getting a rocker/glider arm chair to put in that corner?

Also, a rug?

I would get a mural for the wall.

If possible, I would detach the left hand side of your L-shaped desk (I assume its just a small straight desk that can be moved). Can you fit it as an extension to the right-hand side? It doesn't seem like its being used right now anyway and freeing up more of the left corner would open up more possibilities.

Alternatively, I would leave the desk as is, but tuck a crib next to it and throw a changing pad over the leftside of the desk and use it for a changing table!

I think pictures or something would make the room nicer - like one large abstract canvas in soothing blue/water tones (probably something you could DIY) to make the room feel bigger, airy, and calmer. Or you could do one big piece of shelving or a mantle on that wall and put stuff on it to decorate or use for storage/books.

@T.H.O.U.: Was just commenting a glider or overstuffed chair would be perfect for that corner and see you've suggested the same! Would be useful for either room purpose.