@xxxx,
i too went from private elementary school to public school.
i soon realized that after being coddled for 8 years, i was more or less on my own.
i hated it for the first two years, and then gradually warmed to the place.
joining an after-school club -- ultimate frisbee
-- helped a great deal.
so, my advice to you is give it a chance and try to find something that interests you...
good luck
!