Broken rib that has healed wrong. would like some advice on improving breathing, etc.?

Depends: Generally, a single healed rib fracture not likely to to impede breathing. You should get evaluated by your family physician and trauma surgeon. There are different pain syndromes that can occur after rib fracture/s. It may be important to determine if a displaced fractured rib has resulted in intercostal nerve entrapment.

Time after fracture: If you have malunion or nonunion of a rib fracture, that may be painfull. Usually sharp stabbing, may irradiate along the nerve. Need to allow a year of bone healing because overtime, a callus may form and then it only hurts occationally, bad weather, golf swing etc.