From the description it seems that anxiety
is one of main problem of yours .
You should be happy that extensive investigations have failed to find any disease in you .
Mental peace and healthy habits will help you a lot .
Make the habit of getting up early in the morning and go for regular exercises .
REGULAR EXERCISES WILL INCREASE THE B M R .
Increased B M R will keep you motivated for your daily works ,increase your appetite.
increased appetite with good food habits will take care of your body weight .