Did the physio rule out medial meniscus trouble? The mechanism of injury coupled with what you are describing as aggravating factors would certainly lead me to be concerned about that. When you bend and straighten your knee, do you get any clicking or locking at all? Any feeling of the knee giving way? Where you have drawn the cross looks to me to be on the joint line between your tibia and your femur. If so, it is definitely something to think about!

A serious MCL injury would be easy to spot as your knee would be very lax whilst applying a valgus force to it as shown here

MCL rupture - YouTube

If you have a grade 1 or 2 sprain, this would be harder to properly diagnose, but some laxity and pain along with inflammation will be picked up depending on how acute the injury is.

If I were to test for pes anserine bursitis, I would want to know if you have localised tenderness or swelling, which you do. To isolate, I would get you to perform a resisted flexion of the knee with a bias to the medial hamstring side by internally rotating your hip (semitendinosus and semimembranosus). Also, I'd perform resisted adduction for Gracilis and for Sartorius it would be a mix of a few movements - harder to test. If this recreates your pain, I would suspect hamstring over ligament.

The difficulty is that tests don't tend to rule out everything else and point to the one diagnosis.