I am exactly the same! My boyfriend takes me to many parties and things where i don't know anyone, especially dinner parties where you are sat next to two people you don't know, boy girl boy girl.
Whenever you meet new people, find out little obvious things about them, ask them questions. The more you ask, the less you have to say, the more the person will think you are interested in who they are.
Also, you could always ask your boyfriend to kind of prep you and certain people. Ask him to tell you little details about them, like their interests. Then after you've been introduced you can say "oh i heard you were interested in....." then they get a chance to talk about something, making everything a little easier.
Have a bank of questions in your head of things you could ask people. Just preparing a little before hand will make you a little more confident about going.
Good luck. x x x