Unhealed perineal wound. Healing?

17 months ago I had an induced vaginal delivery with vacuum assistance complicated by a severe perineal tear. A rectovaginal fistula developed but has been successfully repaired with no recurrence. MRI, CT with contrast, and transperineal scan all confirm there is no fistula.  The remaining problem is a superficial perineal wound that has never epithelialized. The skin is still raw and looks almost the same as day 1.  Secondary healing failed. A plastic surgeon refreshed the wound edges and resutured, but the stitches opened on day 14. A urogynecologist treated me with Placentrex for over a month and resutured again, but the stitches gave way in 5 days. I also underwent sinus tract excision, but still no skin has formed.   There is no pain, pus, foul smell, stool or gas leakage. Occasionally the wound bleeds while passing stool. Has anyone managed similar cases? What is the definitive treatment to achieve permanent healing? please help me im exhausted mentally physically with a baby