crobert,

There is no possible way to determine what level of sensitivity you will have in the future. Research shows that second impacts cause more intense symptoms. That does not mean you have to live with a helmet on and afraid to be active. With reasonable precautions, you should be able to go on with your life. As you said, you are a hypochondriac. You will do more to deal with reducing your level of hypochondriasis with therapy and other efforts than worrying about your next head bump.