I feel insecure with what I'm doing?

I cannot be totally sure if it is insecurity but I feel not comfortable and hesitated whenever I'm doing something not productive. Is it possible that it is me worrying if what I'm doing right now cannot bring me to achieve my goal in the future? I'm 16 and I want to go to a prestigious university. Maybe I'm not worrying if I'm wasting my time every moment. Is this OCD feeling/thought? How to stop this?