INTJ's are so cool! I'm an INFJ
*hug* Christain, it's ok. It's taken a lot of courage to post your problem on a pubic forum and you should realize this courage you have within you.
Introversion has many advantages but an extreme level of introversion can cause one to isolate themselves which, as we both agree, is not healthy. Focus on yourself. Focus on cultivating the inner Self. You had the ability in you to put this on this forum, you have the ability to take that further and open yourself to people. You are lacking self-esteem so right now, you have to build up that self-esteem again.
I would say write down how you want to be like, something like:
"I make and maintain close relationships with people easily. I am self-confident. Public speaking is an enjoyable experience and I speak articulately."
These affirmations kind of go into I-M (intention-manifestation) but is also tied into Psycho-Cybernetics. In your mind see yourself confident and self-assured, talking easily with people. Slowly you will begin to adopt the characteristics you see possessing in your mind.