Hi from what you described, I would tend to agree with your dr. that your IBS won't evolve like that. IBS isn't as predictable, but from personal experience (I have mild to moderate IBS), even when sometimes I get a really bad flare up (like I just did about a week ago), I usually get better and get back to the much milder symptoms. When I was under tremendous stress a few years ago, my symptoms did get worse, but when I graduated grad school and gradually get back to a more reasonable and less stressful lifestyle, I've been back to having mild symptoms. So, the key thing is to try not to make the anxiety worse (as the anxiety will add to a already-stressed out system).