Try to build a mock up of the turntable (TT) and engine house area. It is too tight to be workable (maybe).
For example, if the engine house is four inches from the turntable, one track can go straight in, the other will need a short 18" radius section directly off the TT.
Also the turnout near your water tower will have to be a #4, meaning short locos and short diesels will work there, but no steam with three drive wheels.
Again, build a mock up first as I did to squeeze my stuff in.

Notice my curve into the roundhouse. This was done to get the roundhouse as close as possible to the TT.
Most everything is 18" radious except for a 15" approx at the top right with a Atlas Snap-Switch. I only have a couple of locos that will make that turn.