@jenweb This is so frustrating and 15 years is a very long time to live with this. I've had fecal incontinence on occasion after pelvic radiation therapy. I"m glad you came here to Mayo Clinic Connect for support.

Have you considered pelvic floor physical therapy (PT)? I've had PT sessions with pelvic floor specialists and it's been so helpful. I was listening to a radio program a few days ago on women's health and the physicians talked about how effective pelvic floor PT is for the entire pelvic area including the rectum. Your description related to childbirth, age, and menopause fits right into that group. Your doctor would need to make the referral and you would want a PT who is specifically trained in pelvic floor. Here are two websites related to this:
https://menopause.org/
https://www.ucsfhealth.org/treatments/pelvic-floor-physical-therapy
Do you have a primary care physician who will help you with this?