How can nipple depression/crater deformity be repaired? (Photos)

Hello and thank for your time I had gland/fat removal 3 years ago and on the left side too much was removed leaving me with this result. I have been back and forth with the company/surgeon over the last 3 years have seen seen 3 different surgeons all of which have said I need to exercise my pectoral muscles and build my chest up to fix this as nothing else will? This is very difficult to fix and fat grafting will take many sessions with limit success. Whats the truth? Am i stuck like this now?