Will Gluten-free Diet And Lactose-free Diet Cure Severe Abdominal Distention Caused By IBS?

I have severe abdominal distention every day no matter what I eat or drink to the point of looking pregnant. I sometimes am extra gassy. I feel fatigued often, and sometimes moody. I found out I was anemic which has since gotten better from taking iron, but could that be a symptom of my stomach problems? I am a 21 year old female and have had this problem for several years. I have 3-6 bowel movements a day, a couple of them loose, and usually immediately after eating. I have tried gluten and lactose free diets, had a colonoscopy, gallbladder scan, and tested for giardia. I've been told I just have IBS, but I think these symptoms are caused from something. I am getting an endoscopy in the next week. What are other possibilities of what could cause my symptoms and severe bloating? Thanks!