I'm really shy..... How can I overcome that???

I'm in the 8th grade. I have a boyfriend. He's really outgoing. He made the basketball team and I already congratulated him on it. He means everything to me. At school I don't talk a lot. I'm really quiet but I still talk to my friends at lunch and recess. I don't know what to talk to my boyfriend about? Any advice on it? I don't know what to do. My friend told me this, "You're just who you are. You can't change it and don't. He loves you for who you are." I'm taking her advice. I just need to become more talkative around him. He's really sweet and I want to be a good girlfriend. I feel as though I'm being a bad girlfriend to him. I want him to be happy and I want to be happy with him. Please help me...... I need all the advice I can get. Thanks!