You need to identify the cause of the problem.
Do you have restriction when performing certain skills?
How are you impacted by the lack of internal rotation?
Positions that are compromised?
If you have been working on it for a year and not seeing improvement you are not going after the correct thing.
Have you stopped doing the 2 man IR stretch?
There was temporary lasting effect because it is somewhere that needs attention. It may take some time for the change in positioning to hold.
How long did you do it for?