How can I reinvent myself for school?

Well your issues with social skills are going to be difficult to correct. I am exactly the same way with people. Popular amongst my good friends, but when thrown into situations with new people I am the same way rather shy/awkward for similar reasons. Reason why it is going to be difficult to change is because it is a personality trait. You and I are known as Introverts, it is who we are and what we do. It is really difficult to just change. If you really are uncomfortable with it, it might be better to see a psychologist.