How do I overcome my fear of eating new things?

I'm 13 and every since I can remember I have had a fear of trying new food. My diet is awful. It consists of, chicken, pepperoni pizza, chips, bacon, sausages and soup. That's it. It's really embarrassing and I really want to try new things but I can't bring myself to. It's slowly ruining my life as my friends want to go to restaurants for their birthdays and I have to make up and excuse not to go.My parents say if I don't improve my diet I will become seriously ill. Please can you give any advice that will help me.