Graduation: Now what?

Hello! This is my 1st post in 2nd of bachillerat, which is a decisive year for our future. This year I am going to graduate from the high school and start to build my future. As you might know, the next step is to go to the university and do a carreer and that's terrifying for me! I mean, how I am going to know if what I am studying is right for me or not? Will I be good enough? Or will I have a job associated with what I've studied? Well, I hope that! I hope to achieve my goals and be strong enough to get my dream job and pass the job interviews.
Everybody tells me that I am too shy and that I have to be more shameless because in college or in a job I will have to do a lot of oral presentations, comunicate with other people and do this kind of things. One thing in particular that I have to improve is my body lenguage. Last Thursday I did an oral oresentation, I had a nice prezi, all memorized, everything was under control, well, almost everything: I was TERRIFYED! The teacher told me that everything was fine but I have to loose my unconfidence and my shyness, and that's why I have chosen this post from Ted.com. She's sor inspiring, she had a problem with her confidence when she was at college, and now she's a nice psicologist.
I let you the video bellow:

Your body lenguage shapes who you are. 

Body language affects how others see us, but it may also change how we see ourselves. Social psychologist Amy Cuddy shows how “power posing” — standing in a posture of confidence, even when we don’t feel confident — can affect testosterone and cortisol levels in the brain, and might even have an impact on our chances for success.