Well as I am not a doctor I couldn't tell you anything that is like MD related. But I do hear that you lose a bit of weight after a sugery depensing what kind it was.
Any chance you know how much you weighed when you went in? Then you would get a bit of understanding on how much you really lost, if any. To me it doesn't sound bad.
As for the painful stretching. It may feel a little tender when you first start, but it won't be anything dramatical. (all of this comes from experience).
Hope all goes well, keep us (me) updated. heh, I would like to know how you heal up.