Oral?? Kinda shy...HELP!?

So I've gone down on my boyfriend, and of course he really enjoyed it...but now he wants to go down on me. He's been asking for a while, and I kind of want him to, but I'd feel so shy having him down there and of me finishing. We've had sex before but I'm still not 100% comfortable with my body. How do you girls feel about receiving oral? How can I feel more comfortable about it? My friends say I should do it, but I don't know.