I'm exactly the same since I was about 16 maybe? I come across as really shy, a bit awkward quite and introverted, I'm not too bad with people I know (well most of the time) like my family but when I'm meeting new people or in a room full of people something comes over me that I can't control, it completely silences me, takes away my voice and leaves my mind blank.
Inside though I am loud, fun and outgoing, I haven't experienced the real me since I was 14, I'm now 23