The assigning of purpose to a human life is some unholy paradoxical combination of a vast flattering overestimation of its worth, on the one hand, and a blasphemous insulting affront against its dignity on the other. The purpose of life is life itself, that's why it's an insult to demand some other purpose. And by the same token, none of us has the kind of purpose your mind is demanding, that's why it's flattery. If you don't have a sense of purpose, don't worry about it, that's how it is for most people. Try a technique from acting improvisation: say an emphatic yes to the next thing that comes along. Lean into it. Does it lead somewhere good? Keep doing it! Does it lead somewhere bad? Change direction! Repeat. Construct the grand narrative later, as a retrospective.