Have you had any bloodwork or stool testing? Bloodwork can reveal inflammation and stool tests can provide a lot of information on how your digestive system is working. They can test for calprotectin, which can indicate inflammatory bowel disease, and pancreatic elastase which shows whether your pancreas is making sufficient digestive enzymes. Your floating stools and feeling of fullness/not being able to eat much are symptoms of low pancreatic enzymes (and overlaps with other disorders as well). It would be worth doing these tests while you wait for the colonoscopy.