I'm not sure how helpful my answer would be, but I've been were you are now. Surrounded by people who I felt/knew had so much more to contribute than I would ever have. How to act in this position? Enjoy it rather than suffering. Instead of thinking how much you don't know, think about what you stand to learn and experience together with these people. Use them as a resource, be respectful and try to glean off them any piece of information and experience - become a sponge...

Now, this doesn't mean you have to stop trying to do things, but when you do, try to get them to look over your shoulder and review your work as you go. Try to complete a piece of work and then listen to what they have to say about it - write down the comments they give you and try to implement them to create better code. Don't be afraid to ask questions, just be respectful and try to ask good questions - try to absorb the data and consider your immediate question before asking - maybe the answer was already supplied... The best people love to teach, and I bet they would be glad to share their knowledge and philosophy of life with you.

In my situation I tried to do that, and whenever it worked for me, I was the happiest, I never understood why they kept me on, but I had the greatest time, and I like to think I became a better programmer and even man as a result of this experience.

All this is not to say you should underestimate yourself - you probably are much better than you give yourself credit for, but as people wrote here, titles and degrees aren't always that impressive in real life situations and humility goes a long way. So be respectful of everyone, listen, absorb - but take your own lessons from the experience - sometimes you are better off learning what not to do.

Good luck.