Between social media and real life | Social Anxiety

I've just found out about my social anxiety. I've been focusing my whole life about friendship that i basically don't have enough time to think about anything else. Idk if my case is severe or not.

I'm a very active social media user (with few followers lol), i have instagram, twitter, facebook, path, etc. I regularly comment on my friends posts, sometimes using sarcasm and i'm okay with it. I initiate lots of conversation in line and facebook, and people think that i'm fun, outgoing, funny and lively.

But at school everything's different. I feel insecure, lonely, hated, empty. Even my best friend seems like a stranger. I feel guilty, like a pain to everybody else. No matter how many people say that i'm pretty, smart, talented, awesome, cool, great, etc. Those are just lies in my head.. I can't seem to appreciate anything, i feel worthless. I can't initiate talk to people, i'm afraid they'll think i'm weird and boring. Because of that i freeze and become awkward, some girls in my school even make fun of my awkwardness, it really hurts.

I feel weak, small and awkward talking to people i think are more superior, even though they're actually okay being around me. When people bring me in their circles, i kick myself out. That's basically my friendship life in real life. There's usually awkward silence when i speak, and sometimes i even tremble (usually when the person i'm talking to is a popular kid, doesn't apply to guys though. I'm a 'one of the guys' type of girl) I'm THAT afraid to be judged, i don't have any faith in myself.

I don't have any problem in having new friends though. EXCEPT they're a well known-instagram famous-social butterfly. Then i have a problem with that.

I'm in 12th grade, and I'm supposed to be focusing in applying college and universities. But I'm not. I'm really scared that this anxiety will eventually ruin my opportunities.