I will lose if I be myself?

The time has come to bite the bullet and do whatever you need to in order to achieve your goals. If that means being outspoken and participating in discussion, then you'll have to force yourself to do it. It's a tough gig, so good luck. Ultimately your dream is more important that what others think. Ironically, extroverted people tend to be less concerned about others than introverts, so chances are you won't be judged as harshly as you fear.