I rarely sleep for less than ten hours, I live a lifestyle that is anything but demanding, and I get a perfectly adequate amount of nutrition. In spite of that, I spend every moment of every day feeling drained, often severely drained. It gets worse if I haven't slept a lot--twelve hours is ideal, and anything less than nine will leave me very sleepy for the rest of the day, on top of being physically exhausted.
It also gets worse after I eat. Regardless of what it is I've eaten, after it's been sitting in my stomach for about half an hour, I start to become so drained that simple things like getting up and walking across the room make me lightheaded and cause my pulse to race (which is a problem all throughout the day, but compared with after a meal, only on a minor scale). If I were to force myself to engage in any kind of vigorous activity at that point, such as going for a brisk walk, I feel that I would probably end up passing out or at least come very close to it. And having to refrain from vigorous activity after meals is far from the only thing that this does to me. It leaves me, in general, with a lack of energy to do anything; even simple thoughts and feelings are difficult to muster up and focus, because I'm so weighed down all the time.
Looking at my reaction to meals, I feel that all of this must have something to do with some kind of food intolerance, but so far I haven't had any real leads. I've tested my resting pulse, blood pressure, and blood sugar levels before and after meals, and come up with nothing abnormal. I've also had numerous blood tests, a heart test, and even a bodily X-ray, and none of them indicated that anything was wrong. I also tried tweaking my diet in terms of what I eat, when I eat it, and how much of it I eat, and the only thing I learned from that was that the larger a meal is, the more tired it tends to make me (not sure if this is related to caloric content or something like that, or if it's the actual size of the meal that matters). Another thing I tried to do was to get more exercise, but I was so tired all the time that it was very difficult to find the energy to do that, and after keeping at it for several weeks (there were two or three instances where I tried that), I still wasn't getting any positive results.
So basically, I'm wondering if anyone has any advice or helpful experiences that they could offer me. I would go to a doctor, but I feel like I've run into a dead end and might start to look like a hypochondriac.