Not Cathe but i'm a physical therapist so I figured I would chime in. I think that you can do most exercises without an issue. If you feel pain doing anything, stop immediately. Because of your diagnosis, your going to want to avoid any type of back extension exercise as this will cause more compression on the nerves (this is true only if you have foramenal stenosis vs central stenosis). You want to be very mindful of maintaining a neural spine with all activity. I'm sure your PT gave you some good core strengtheners. These may seem basic but they really build the strength in the deep core muscles. Feel free to ask any questions. I hope Cathe responds to you so she can share her opinions.