It also could be that you are just naturally introverted. I am like that. I need to get away from a crowd after a while to recharge. But when I am charged I am just fine at socializing and interacting. Don't forget, failure is only a learning tool to make yourself better, it's going to happen a lot in life, so make notes about what happened, learn from it, and move on. But, since you are introverted you most likely are naturally laid back. So take that laid back energy with you to the party to make other people feel relaxed. It works fine with me. Don't get overly dependent on using alcohol as a crutch for social interactions, it could cause you severe problems later on in your life.