The whole wall won't build?

[solver]

One of the keys to your design is the stair. As is, it does not work. The red line shown is less than 6' and the steps do not reach the 2nd floor.

 

I suggest getting them and the stairwell set before working more on the 2nd floor.

[solver]

Here is one idea. I've reduced the bathroom ceiling to 90", and made the ceiling/floor structure thinner using 2x6 material. This lets you use fewer steps to reach the floor above, and they are not so steep.

 

Also rearranged the bath a bit, moving the washer outside.

 

Space for water heater under the stairs with access from the exterior.

 

You could also extend the bath along the back wall towards the outdoor shower.