Most doctors don't really understand chronic pain.
People who have it for a long time are used to hiding it. So doctors who are looking for "signs of visible discomfort" are not going to find it, and this is going to make them think you are a hypochondriac and not an excellent, well-practiced actor. It's a good idea to establish some way to communicate with each provider when you're in discomfort. If nothing else, this will save you the frustration of having to read the puzzled phrase "no signs of visible discomfort" so many times in your records. : )
Since they don't understand it (its causes and especially its effects), doctors will really just not be able to factor it into your overall situation. It's frustrating, but if you set that bar low, you will be less frustrated. It can also be a gate you use when meeting new potential providers. How much do they know about chronic pain and what do they understand about its effects? Can they factor this knowledge and understanding into the puzzle that is your symptoms? If so, they may be better able to help you.
At the very least, they won't frustrate you as much by throwing their hands up in the air and getting mad at you when nothing they try seems to help and they get pulled up short by their own limited knowledge and understanding. Not all doctors do this, but some do. Try to avoid them, if you can. : ) But also try not to hold it against them. No one likes to be reminded sharply of one's finitude.