It's unusual for a full enema to empty with just one pass. If I take in 1.5-2 liters, it usually comes out in three waves, as it empties from each section of the colon.
I havce also used just warm water at times, but try to keep really hydrated, otherwise I can end up reaborbing some of the water (and toxins). When you are bloated, that's not so great.
Your digestive issues and constipation could be symptom of parasites, and those would not be detected with a colonoscopy unforttunately.