Hey !!
It`s a pleasure to respond to needy people always ..Well Is there a way that i can reach you so that i can explain and demonstrate to you the major exercises .. Its pros and cons ??
Is there a way where i can see your reports (probably via mails ) and giude you in the perfect manner ... I assure you would not need a 4th operation at all ... All your wasted muscles can really be strengthened .. What you need is serious dedication and focus on the exercises..And nothing else.. There`s nothing impossible.. you can always incresase you range of motion ...
Since ,the lack of strength is a major reason why your shoulder mobility is not more than 90degrees..Stifness can be a reason but it can be treated..
Regards,
Radhika