Just making sure: you had a bunch of tests before you were diagnosed with IBS, right? Some doctors skip that and just assume it's IBS because the symptoms fit and it's a fad diagnosis. However, other things need to be ruled out. IBS is a diagnosis of exclusion. Too many other conditions mimic the symptoms (which can often be vague and vary from person to person).
If it is IBS (or even a lot of other digestive disorders), I've read some research and heard some anecdotal evidence that Probiotics and Prebiotics can really help. This is stuff like yogurt, Probiotic capsuels, etc. They help build a culture of "friendly bacteria" in the intestines to aid digestion. It's all about balance. Do some research into it. It is completely harmless and relatively low cost. Just don't take the pills with too many types of bacteria in them. You only need a few kinds. Too many can cause problems, too.
Also, a food journal where you track your symptoms related to things you eat can be really helpful to identify trigger foods. Common trigger foods include caffeine, alcohol, dairy, artificial sweeteners, red meat, etc. Some people have more sensitivity to some than others.
Reducing stress is important, as well, when you are having symptoms (stress is not the cause, but it can defiantly make things worse).
Anyway, just thought I'd put my 2 cents in. Hope some of this helps someone. All this research might as well be put to good use. I did it for my mom, but she's too stubborn to listen to me and her doctor didn't give her any information--just gave her the diagnosis and sent her on her way. So I guess she'll just endure her symptoms until she gets fed up with it.