Hi Swing, Welcome to the group.
It's troubling to give some part of you enough time to heal. I've had two "frozen shoulders" one of which they operated on. (That's not all of my broken stuff list, but enough for this discussion

) Did you ask your doc about some type of physical therapy for your knees, do the things you are doing seem to be enough?
Is your shoulder something that will need repair, like a torn rotator cuff, or might it be a frozen shoulder? It's called adhesive capsulitis and in my own terms, is when the lubricating sack of the joint slowly dries up, the tendons tighten because of favoring it, and you literally get to the point where you can't move it without a great deal of pain. It is more common in diabetics.
After my first frozen shoulder, I decided I didn't want anyone to have to operate again because it took years, not months to get it moving correctly again afterward. When shoulder number two began to do its thing, I started stretching and flexing it myself and avoided any medical intervention on that one. They're both normal now, thank goodness.
I'm thinking you, having mentioned pitching, have a repairable injury. Tiger Lily's suggestion is a good one, water stretching exercises might help while you wait.
Again, welcome. Looking forward to hearing more from you.
Mich