First of all calm down. Listen to some relaxing music or run for a quick jog. Then realize that is the boy’s job to start start the conversation and think of topics.Just don’t give him one word answers. For example if he asks, “what do you do”? Don’t answer secretary and sit there quietly. Try to make his job easier by bringing up your own interesting comments, ideas..etc. Just be yourself and calm down. Take deep breaths and try to enjoy yourself. Try to relax and look relaxed. The boy is also usually nervous and if you look relaxed he will also loosen up. Do you have any brothers who can give you a practice run through? Right before the date say some Tehillim and think calm thoughts.
Have fun and good luck!