You said you had a Union representative with you when you met with Occupational Health and Safety officials. Can the union offer you any further advice, or connect you with others who have gone through anything similar? Can they do more to represent and advocate for you or have you exhausted the appeals process?
I'm sure you'd rather retire on your own terms when you feel ready rather than feel you were forced out. Retiring may be the right choice but it's a tough decision to make on your own. The more local support you can get, the better.