Concern for your child is perfecly normal - I worry about all my girls driving in this seriously icy weather, which none of them have experienced - and they are 33, 31, and nearly 20!
What you have to do is not let it become an obsession.
I know you know that you cannot protect your daughter for ever, she is going to make mistakes, get hurt physically, emotionally and spiritually, which is all part of life's journey.
You must learn to support without smothering, and trust your daughter to remember all the safety advice you have given her.
Remember, while you fret and worry, she is busy having a wonderful time, so don;t beat yourself up all day, you need to keep a sense of proportion or you will never be happy letting her find her independence.
Parenthood - who'd have it!
I would - and so would you, it's wonderful!!!