As somebody that never felt they had some higher purpose I can't say that I feel any need for it. I can understand you feel like you lack something when lose a higher purpose you've had all your life, but that (for lack of better words) sound like you have developed a dependency on that purpose. What you describe is common for many people leaving religion, but it is also something that is overcome by most after (sometimes a long) time.

Personally, my values of making the world a better place for future generations while having some fun seem to do.