dude, i can completely sympathise with you here, i had something similar recently before finding this community and as tcomea2 has said it is all about inner game!
One of the best things I can recommend is reading a book - 'what every BODY is saying' by Joe Navarro, it deals with body language, (plus its an easy read,) and then making a conscious decision to adopt and display this confident non-verbal communication in every day life, at work, in bars, just walking down the street. eventually, you'll start to reprogram your subconscious mind and this will become natural to you, you will start to radiate confidence, and the thing is, its surprising how good just adopting this body language makes you feel!
Taking pride in your appearance also does wonders for you, i'd advise to constantly Peacock yourself to some extent - personally, I feel my best after having a shower, clean clothes, clean teeth etc. and again, makes you feel good about yourself. You'd be surprised how much grooming can do for your confidence in a situation.
in the getting to know stage, its important not to barrage them with interview questions, they've heard a million times. use some set pieces to tell them a little about themselves and allow them to expand on it. also its worth telling stories that escalate your personality (without boasting), remember to be semi-vague/ leave loop holes out for effective story telling, it encourages them to ask questions / tell their own experiences etc.
i mean these are just a few of the things that have helped me with regaining my confidence