Your mistake is referring to an act of Congress for help in determining the definition of “natural born.” I’m sorry, can Congress amend the Constitution?
It can’t. All it can do is help to show what the commonly understood meaning of the term was at the time. So, the first congress said that the children of U.S. citizens born oversees “shall be considered as natural born citizens” unless the father had never been resident in the U.S. This shows us that the commonly understood meaning of natural born citizen at the time the constitution was written included children born to U.S. citizens overseas. This should put to a final end this birther nonsense.