I'm sorry you're having such a frustrating time. You don't mention how many bowel movements you usually experience each day so my situation may not be similar to yours but I'll share my limited experience with colonic irrigation.
I, too, wanted to start Liver Cleansing and needed to make sure my bowel was clean first. I had three sessions in three weeks with nothing much more than gas as a result of my time and money. My therapist said she couldn't feel any peristalsis and I got almost no material to release. I've been taking ground flax seed for bulk for the past three years along with trying to clean up my diet of refined foods so I usually have 2-3 bowel movements a day. I asked on this forum if the colonics were doing me any good and the response was that my colon was functioning just fine. So... I decided to go ahead and do my first liver cleanse and I got modest results with no discomfort. My colonic afterward, however, was quite a bit different than the previous three. I had good peristalsis during the session got quite a bit of material. I'll be doing another liver cleanse this weekend with a colonic scheduled for Monday so I can't yet tell if it was just a coincidence or if it's going to be a more permanent change.