It is important to be faithful with your prayers, but perhaps praying in a quiet and inconspicuous way at school would be the most beneficial thing to do. We are not to be ashamed of our faith, but we are also to avoid grandstanding and making a show of it for our peers. Christ warns us about praying in public to be seen, and you seem very aware that this would draw a lot of attention to you. In fact, you even seem to anticipate harassment because of it. My advice would be to quietly pray to yourself before meals at school, and perhaps be more formal and precise (standing, chanting and facing east) when at home, "in your closet" as it were.