Framing looks good.Two observations: The curb,I find it too high with those cripple studs.Three 2x4's would do. The drain,I would put it in the centre so that the slope of the mortar bed will be more gradual while keeping the perimeter level.With the drain where it is the slope will be steeper there.Looks like it could get near the centre without notching another joist.
I would entertain the idea of using Schluter's Kerdi system here.The drain and the membrane.With this system there is less work to install the substrates...the mortar bed and the backerboard,less work for framing too...and the substrate will be completely waterproofed directly on its surface.
The traditional methods allow the substrates to get saturated.To build a shower using traditional methods by-the-book takes longer too.
A shower where the surface directly under the tile is protected by a membrane is a better shower.
www.schluter.com