I sympathise entirely. I had a thread a little while ago about how stressed I got going to a new doctor - worrying I wouldn't be believed or taken seriously. It's happened so many times in the past that even now I have a diagnosis and have had posititive test results, I still worry. I worry they'll say the level of disease indicated on objective tests doesn't warrant the level of symptoms I experience, and therefore find some way to blame me for my symptoms still . I always thought getting a diagonsis would stop the fear of being dismissed, but it was such an anticlimax for me.
I have found a couple of good doctors though, eventually. It seems to be a matter of finding the individuals who do believe me and treat me well. And stopping going to the ones who don't as soon as possible - don't get upset, just don't go back, and go to someone else as soon as possible until you find the right doctor. It does embarrass me sometimes how many I've seen, but if they don't treat me properly then I try to remind myself I'm entitled to find someone who does!
It sounds like this appointment didn't go so well, is that right? Keep going - don't take this doctor's attitude as any reflection on you or your severity of symptoms if he wasn't concerned. Some doctors only seem to care if you're at death's door. If objective signs show you're not that sick, take that as a good thing and see your doctor's lack of concern as a sign you at least don't need urgent attention and there's no immediate threat to your health.
But I know it's no help to be told there's nothing that wrong when you're quality of life is being affected by symptoms, and it hurts when doctors seem to imply you're a hypochondriac for caring about this. It seems they do this to many patients, so don't take it personally. You'll find the right doctor and get some answers eventually. Some patients end up finding out they actually have something wrong. But as I said, for me the diagnosis didn't solve these types of problems with doctors, so maybe it's not such an important thing to come back with a positive test result after all. Some do end up with a "functional" diagnosis like IBS, but even then you can still hope to find a doctor who recognises that IBS causes suffering and needs treatment.