I test out as an INTJ too, although I would have guessed I was an INTP. I scored low on the "J", so not too far from Perceiving.
I've learned to handle being in large groups, and actually chose to be an instructor as I gained more confidence in my ability to be in group situations. It really helps when you have topics you excel in - not just know something about, but can be considered an "expert" by most. This makes you interesting, stimulating - and someone that others come to for advice. It's easy to make small talk when you've got the knowledge and those you talk to don't .. *L*
And I also learned how to just observe people. I can be in a large group and sit peacefully alone, watching how people interact. You see things in people that you don't tend to notice when you're talking with them. I smile at things that happen, and it's easy to keep a pleasant (i.e. not arrogant or unhappy) look on my face when I'm people-watching, because people are just so darn amusing.
It takes time to develop traits that allow you to be comfortable and confident in a social setting, when you're naturally an introvert. But it's worth it. I didn't want to limit my life by always avoiding social contact. So I pushed my way through all the awkwardness, all the angst, all the "oh my God I don't fit in!" thoughts, and found that there's really no one better than I am. I'm not saying they're WORSE than me, just not better.