Hi there!
I was exactly like this, I have small bowel disease which in my case means I don't suffer from D. It's only recently I've started to get the more classic symptoms of pain, blood & mucus etc. I made the mistake of thinking that because I don't have big dramatic flares that foods don't effect me. With a bit of listening to my body I have discovered that isn't the case. I'd definitely recommend a food symptom diary, I certainly didn't feel I needed it at the time but it did help me narrow down.
The problem with me when diagnosed was that I was barely eating anything at all, pretty much just bread & cheese. As the nausea & vomiting have calmed down and I've re-introduced things and watched closely, I know a few things that are best to stay away from!
Best of luck x