Why do I feel so incredibly exhausted all the time?

I don't know why you don't go to the doctors. That being said, coffee does make you tired. I have to use decaf. Coffee doesn't let you sleep at the right time or something. Exercise makes you tired and have to sleep a lot and a lot of stress, worry. Use your intuition more, it is less stressful. Eat more protein, that stands by you. I have higher longer energy with protein. Carbohydrates,(breads, pastry, sugar) wear me out. Other stimulants have the same affect and you may still be growing. Some grow until 19 or older. Coffee dries you out too. It still sounds like not enough water or something is drying you out like diabetes, not enough iron for some of the symptoms. Boy, it doesn't sound good, except for lips I blot mine dry or else they chap. Nails can be calcium. I sure would get professional help.