I Have Been Diagnosed With Ibs I Have Had Chronic

I have been diagnosed with ibs I have had chronic diarrhea for years I go to the toilet anyway between 5 to 12 times a day and it is always soft or watery. I have had a colonoscopy recently which has ruled out chrons colitis and coelic disease. I am very overweight although I would say my diet is healthy I am over 23 stone and I have to use the toilet every time I eat or drink sometimes I can't get through a meal without needing the toilet. I have been tested for thyroidism too which was negative. I feel drained all the time and I really don't believe this could just be ibs. The gastroentrologist has said that a healthy diet and exercise will solve my issue. They do not believe me when I say I eat healthy I cannot live like this everyday of my life.