Why am I acting like this?

I'm 16 years old now. Ever since I was about 13 I noticed a huge change in my personality. I started to become very nervous, quiet, and often not know how to act around people or in social situations unless I was around close friends or family (people I feel comfortable around). As the years have gone by it has just gotten worse and worse. It started out with this nervous neck twitch. Anytime I notice someone looking at me, my neck starts to grow very stiff, and if I try to move it, it spasms out of control for only a few seconds, then goes back to normal. Please don't tell me it's turrets syndrome, because its not. It only happens when I feel I'm being watched. Then, as time went on I developed a fear of presenting/speaking publicly. I become sweaty, my face, neck, and chest turn blood red and my voice and hands shake like hell. And of course, my neck spasms out of control all at the same time. It's terrible! I also developed a fear doing the simplest, stupidest things like walking, dancing, or running in front of other people. I feel like people are making fun of the way I do things, so I feel as if I have to try and do them perfectly. I don't understand my behaviors. Does anybody else have or know anyone that has similar behaviors to any of mine? What's causing these fears? How can I get rid of them? Is there even a name for this? I feel as though this is ruining my life. But there is one other person in my family that, since I've been older, I've noticed has a lot of the same social behaviors I have, mostly all of the ones I described above, and it's my aunt (my mom's twin sister). Could my behaviors be hereditary? I'm so afraid of being like her when I grow up. I mean I'm not trying to put her down because I love her dearly, but it seems like her behavioral disorder or whatever she has caused her a sad, lonely life. She's almost 40, doesn't go out with friends often, not married, doesn't date, in fact she said she's never even kissed anyone before. So far, I'm on the same track as her. Plus, she dropped out of college and now works a factory job for minimum wage. Please help so I don't live a sad, lonely life too!