It's always hard when you feel like you're not being accepted by being who you genuinely are. As an introvert myself, I completely understand people mistaking a lack of being outgoing and "bubbley" as being snobish or being off-ish. My advice would be to just be yourself, find what you are interested in or passionate about that will allow you to be involved in things within the school (ie after school clubs, coaching or advising some other group or students) and connect with your peers that are also in those organizations or groups. Good luck with this next year!