Post sigmoid volvulus surger

It has been 3 years since I had a part of my sigmoid colon resectioned.  I still have concerns over how to improve my bowel movements.  Before I had surgery, I would have a BM no more than once every 3 days.  Now I have them once a day or once every other day.  It seems that the bm drops into place a little while before it is ready to be released.  It takes a lot of strength to push it thru.  I am adding fiber semi regularly, but it doesn;t seem to help.  What causes that feeling of fullness in my colon prior to the actual release of my bm.