How do I stop feeling so clingy and insecure?

I just made things official with a girl last week after a lot of crazy things between us so we've both been happy. But I want her attention like...a lot.

She has friends and stuff that she spends time with whereas my life is basically work and her. She's very outgoing and I'm generally withdrawn and don't say much. It's a week in and I'm already freaking the fuck out she doesn't want to spend time with me or I'm being too needy.

I know it's fucking insane and irrational I just need to figure out how to shut my fucking head up because I really like her and want this to work.

For whatever its worth we talk a little bit on facebook almost every day and see eachother about three times a week at college, and have one day of spending the night together and stuff.