Have you been diagnosed with colonic inertia? This sounds more like colonic inertia than IBS. You should see a GI and request a sitz marker test. Once a diagnosis of CI is made you will have options for treatment that may include surgery.
Well it's too bad you can't get insurance to cover biofeedback because it helped me immensely when I was incontinent! Surgery may relieve you of some of your discomfort but it won't be a magic cure. I'm sure others who have CI will chime in and report on their successes.