How about flanking the window will billy bookcases? Paint over the green wall an off white and just pick a color you love for the bed wall. A stylish chair for your desk and maybe "industrial" looking bedside lamps will "man" it up. :) Plus, get a cooler looking desk chair...in a color that you paint the bed wall.

Well, for lack of a better idea, since you find it a drafty little space. I'm assuming the draft comes in on the right? Most of the necessities in the area are located of the left side; i.e. vent, thermostat, light switch etc. What I would do I think is caulk up the drafty spots, maybe even add sized poster board wrapped in batting I covered in a gorgeous fuscia with diagonal grosgrain ribbons every which way covered with a heavy velvet to be attached to the area above & below the window. (Of course remove the drapes that are hanging in there). This for the purpose of using it as a pin-it board for notes. Attach a table height board covered in felt to carry across the full width of the little room. Leaving just enough space for a comfortable little antique desk chair. Paint the back wall a bright cobalt blue, paint the ceiling a silvery pearlescent white. Find a way to attach a clip-on task lamp. And stretch a heavy duty enough wire across the top of the opening and complete it with a heavy doubled velvet drape with a drooping valance. Place a swag with fringe & jewels on it to be closed when not in use. Voila intrigue is yours!

An entire wall of built-in cabinets and hooks and cubbies for your crafting stuff (and perhaps filing-type stuff and printer for the office). Take a good look at what you have and think about how best to organize and store it and what could be displayed to be pretty and what should be hidden behind curtains or doors. A fold down ironing board on a wall or back of a door somewhere would be great. A nice desk and filing cabinet for the office side... or perhaps a great big table in the middle under the window, wide enough to function for both of you facing each other? A nice curtain rod would make a big difference too. Preferably just about floor to ceiling. I'd put a splash of colour on the walls and keep the curtains simple, but you could go vice-versa too. Something like this: [https://www.houzz.co.nz/photos/modern-bungalow-phvw-vp~4999540[(https://www.houzz.co.nz/photos/modern-bungalow-phvw-vp~4999540)

A lovely rug on the floor would be nice. You seem to have some space, yet your table is pushed against the wall. You could consider a bigger table for centre of the room or making it into an office / desk / book shelf / comfy chair. You have lovely sun coming in. Even a bean bag and a small coffee table could make a difference. A medium sized plant would also look great. Set a budget and stick to it, re-purpose things if you can and / or buy second hand so you don't break the bank. I love the little air vent on the floor it looks like a little mouse house. Maybe you can get some removable stickers and make an art piece or at least a little mouse running to the hole.