My Darling Daughter,
This is your first formal dance, replete with dress, hair, flowers, dinner and the event itself. You've already discovered what a heart wrenching and anxiety provoking experience this type of thing can be. Let's be honest - it's hard to get everyone paired up with the appropriate escort, and boys at this age are at least half the problem. But you were graceful in your acceptance of the invitation, even though you would probably have a lot more fun if you were going with another.
However, all is not lost. I'm glad your going in a group, because sometimes the expectations around special occasions are simply too high. Your escort is also "just a friend", which will make it easier for both of you. With a group - if you get bored you can just go hang out or dance with someone else for a while.
I know you're somewhat nervous about doing the right thing and acting the right way. Rest assured, you are well equipped with a full arsenal of social graces and personal maturity that supersedes your chronological age.
So enjoy yourself!! Dance till you drop, remember to say thank you and resume normal life in the morning. And don't forget to get all the hairpins out before you go to sleep. Beautiful tresses like yours deserve a great up-do - but it will be a tangled mess resembling a well-spiked porcupine the following day if you don't get those pins removed. And keep your flowers - they'll dry nicely and remain a wonderful memento of what I hope will be a really great evening for all of you.
And if it sucks (and it might) - the morning will still dawn. Your tresses will still get washed and fluffed and you'll move on - truly none the worse for wear. And keep the flowers anyway!