It takes usually 4 to 5 hours for someone to clear out the first chapter (the school competition), so you are definitely an efficient kind of player (I suppose you didn't activate the game aids, by the way?).
There's a great deal of content after the school, so I can only encourage you to continue your adventure. The next chapters are quite different from the first one: in Chapter 1 you are restricted to the school, but in Chapter 2 and 3, you are going to get some travelling.