I also have IBS and was diagnosed years ago, but I never heard of different classifications that you mentioned, IBS-C or IBS-D. Mostly, I classify the severity as "day-to-day", workdays usually being the worst. I haven't tried consuming live cultures other than yogurt, and even then I have mixed results. Have you gotten far in your research on the types of bacteria, and do you have any resources you could share?

Edit: just read about differences between IBS-C and D and it definitely sounds like there has been some headway in the last 15 years since I was diagnosed (back then it was mostly a prognosis of "here's a colonoscopy, sorry not much else we can do"). I should definitely get re-evaluated. Thanks for mentioning this.