Originally Posted by Kelb_Panthera
Your original body's not on the astral unless that's where you cast the spell.
"You project your astral self onto the Astral Plane, leaving your physical body behind on the Material Plane in a state of suspended animation."
I believe the original body is given in the spell to start out on the Material Plane, so you'd need to cast the spell from there. Of course, you can move your body from the Material Plane to somewhere else after the spell has been cast, but you do seem to need to start out in a specific place, or at least on a specific plane.