Rather than make a closet in the bathroom, have you considered one of those beds that is like a bunk bed, except that the space under the top bunk is made into a desk/cupboards/whatever?

Thank you for this thought! My father is a pediatrician and has seen too many injuries with children falling off the top bunk. I promised him we'd never have bunk beds. Here is a really rough drawing of the space. We originally toyed with bringing the wall at the foot of the tub forward and creating a more traditional closet that opens into a bedroom/bathroom hallway (second sketch below). We decided against the latter because it made the bathroom smaller-feeling and the closet itself wasn't going to be particularly awesome either.

OK, if it's a kid's room, why a queen bed? You could put a single along the wall with the head where your desk is, one of those freestanding wardrobes either against the wall where the headboard of your proposed queen bed is, or on the wall with the door to the hallway, and the desk in the space left over.

So does one square equal one foot? 2 foot doorways? Yikes! Hate to tell ya, but I dont think that's legal.

I would put a small 3 x 3 shower where the tub is, so you can reduce bathroom to 6 ft wide x 8 ft (incl shower). Use a twin or I think there are these super singlest that are 48 inch wide.

PUSH bed to the right, so head is where you have closet now. Put closet down at the other end in corner where desk is. Put desk to the LEFT of the door as you come in (or to right as you're going on).

Youll have to give on some of the components - what you have now wont fit.