Bunk Bed Plan
You like this bed, because it is twin over queen:

Basically it is a loft bed, with a matching queen bed frame below:

I purpose we build the loft part of the bed you like above, and try the queen below on the bedframe it is currently on. If you guys like it, then we could build the bed frame for the queen to match.
If you don’t like it, we can still use the loft bed and do something like this. Only the desk and bookshelf won’t really be attached, but if wanted we could find some way to screw to the rails of the above bed.

This bed is made out of oak, so pricey. We could make it out of pine and paint it white for a lot less.
I have this desk that is solid wood that we could paint white and update the handles.
It is not a very big desk but she would need a big girl chair but it would give her a little room to grow. From floor to desk top is about 29 1/2 .
The desk top is 41 1/2″ wide and 21″ deep. A twin mattress is 38 inches. If you add in the rails it would close to the same size as the front of her bed.
Or we could look for another desk.

The only issue I see, is that whole bed would have to set in the middle of a wall so she could set at her desk AND still access the ladder on the other end of the bed.
Maybe we should wait until you get the house and measure things in her room…..ROFL