Everything can be changed or improved, if we try and do practice.
Don't believe what others say about you. Turn it into a positive and powerful energy. And take it as a challenge and try hard to prove yourself. You have enough time. To make everything better.
Don't think you are introvert or extrovert. It doesn’t matter. These are only mental blocks. A better idea is to think some areas you did not practise a lot so now these become matter of concern.
Have company of positive, energetic and mature persons. And keep a distance from such people.
Instead of thinking all these things better idea is to pick one problem at a time and work on it, improve and then pick next one. If you try in a very planned manner. I am sure you can change yourself completely in less than a year.
Read some good books starting with on personality development.
Read newspaper editorials.
Work on language and communication skills.
Sharpen your logical, analytical and thinking skills
Take your subject classes seriously.
Join Gym, Play sports, Take part in all college activities, Take part in inter-college activities.
For one year do experiment with yourself, your skills and your abilities. Come out from your comfort zone. Set an example. Become an example. Prove there is nothing like Introvert and extrovert. The thing is matter willpower, self-discipline, hard work, practice, positive and problem-solving attitude.
Chase your dream. Achieve your goals and become motivation for many other.