Start working on external rotation below 90 degrees of abduction.
Set the humerus at about 45 degrees of abduction and about 30 degrees flexion using a thick towel roll(this will put you in the plane of the scapula).
Use a broomstick or a cane or whatever to help push the shoulder into external rotation. This should be more comfortable than up at 90 degrees of pure abduction like you have in the photo.
The sticking point sounds like an impingement. Question is whether it's a correctable one by improving mechanics or if you've got an acromial morphology issue.
If you can get some soft-tissue work on your subscapularis and infraspinatus as well and make sure you're addressing internal rotation as well. You older photos were indicative of some significant stiffness in all planes.
Bill
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