People over-estimate me?

You seem to be intelligent. You may suffer from social anxiety disorder or schizophrenia but that would not make you less intelligent than the average person. To the contrary, there are a lot of people in history that were considered geniuses that also suffered from mental illness. You need to get in to see a doctor to determine the proper diagnosis for you problem. Medication and counseling may be of great help to you. You are young and you have your whole life ahead of you! Make the best of it and get help so that you don't have to suffer with this any longer than you already have. I wish you the best.