I had Rectal Resection in 1986 which removed part of my Sigmoid Colon (I do not know how much). My experience has been similar to yours. Over the past year I have discovered that I can have some impact on my bowel movement, diarrhea, constipation events by alternating between one Dulcolax Soft Chew to relieve constipation or one Loperamide to stop diarrhea. Timing for either is important and has required experimentation and keeping track of bowel habits after either therapy. I recently started an App for overactive bladder and fecal incontinence through Johns Hopkins Physical Therapy and it is also helping. I am happy that after 40 years, I am making progress although the outcomes from surgery and radiation I expect to remain.