Thank you for that much of information , and specially the X-Ray. Your Physio is half right and half wrong. WRONG about increasing in the stiffness. Right about discontinuing physio (i your range is somewhere around 0 Degree - 120 degree (that is from straight to elbow bent forming an angle of 120 degrees ) which is 5-10 degrees up from the functional use of elbow . it should not affect your daily activities.(most of them) . normal range which is till 135 degrees flexion, can be achieved by holding the elbow in flexed position for 30 seconds and (normal range + a bit extra (1-2 degree) range (till what you can bear without pain)) and relax for 10 seconds. and continue the same till you are satisfied with the desired normal range.
Next Steps
Do It Yourself or find a better therapist who atleast knows that THERAPY IS FOR NORMALIZING and NOT Enhancing STIFFNESS.
Health Tips
DO NOT OVER STRETCH thinking that you can do it in a day or two, certainly it will take some time about few weeks. but be calm and STAY HEALTHY.