Hi Niki,
I also have IBS (Irritable Bowel Syndrome) and am fighting weight loss. I went through every test before I was diagnosed with IBS. I finally saw a Naturopathic Doctor and she helped me get my life back. My IBS was a result of having Candida (it's like excess yeast in the bowels which in turns affects it functioning ability). This was my reason at least. I now have a normal life and can eat pretty much anything I want. Every once in a while it may creep back but I get back on track and watch what I eat (sugar, yeast,etc) , and it clears up quite quickly. When I was first treating it, it took a while to clear up. I have been on Weight Watchers forever and am on it for life. It really is a lifestyle change, not a diet. I have 10-15 more lbs to lose before I hit goal, and I fight it everyday, well, almost!
Don't lose hope! You are not alone!
Good luck with everything,
In For Life