Technically, in order to receive a diagnosis of irritable bowel syndrome (IBS), your symptoms must meet the Rome III criteria. The criteria refer to "persistent abdominal pain or discomfort" as being necessary for an IBS diagnosis.
Many doctors will give a label of "IBS" to any chronic intestinal problem once other disorders have been ruled out. For some people, a more accurate diagnosis would be:
Your doctor may just be using the term IBS because it is more familiar to people. If your doctor is confident that your symptoms are due to IBS or one of the above FGDs, then you should probably view your lack of pain as a good thing, rather than something to be worried about.
DISCLAIMER: The information contained on this site is for educational purposes only and should not be used as a substitute for diagnosis or treatment rendered by a licensed physician. It is essential that you discuss with your doctor any symptoms or medical problems that you may be experiencing.