I certainly sympathise with that. Actually the mother of a friend of mine (diagnosed with bipolar and been treated for it for almost 30 years) told me from personal experience to be very very careful what I say to pdocs as complete honesty and trust put in just any pdoc can do much damage. And I have felt some of that myself. I have the same phobia about antipsychotics - I have tried about 5 of them and none agreed with me, and I firmly believe my biology simply rejects them as a type of medication and trying another 5 wouldn't change anything.
And my other fear is gaining the additional label of a personality disorder, which a pdoc had at some point convinced me I had before discharging me from his care. I have nothing against that particular disorder, apart from the fact that I don't have it!! Therapists I have seen don't think I do, and a psychiatrist I saw at home is certain that I don't, and from my own reading I know I don't. And no matter what my problems are, fooling myself about these things is not one of them. But it took me a while to shake off what the doctor had instilled in me and stop accusing myself for episodes under thoughts such as 'you just need to reprogramme your brain'.
The way pdocs sometimes reduce bipolar symptoms to a single list that can fit on one piece of paper and anything outside it be thrown on the pile of 'personality issues' makes me feel sick. And how ready they are to throw you on zyprexa and the likes just to keep you sedated enough not to be a 'threat', without even having established if you are a threat or what exactly is wrong with you. I apologise for how this turned into a rant....I guess I really hate my previous pdoc

Bottom line - if derealisation doesn't get in the way of functioning there is no reason to tell.