"How do I get rid of that feeling? How do I make the days go by faster?"
Feelings are associated with thoughts. Missing her is a normal reaction. It becomes unhealthy when your day is dominated by that. Feelings can be managed as you manage your thinking (start catching yourself thinking of her and then what you tell yourself and redirect these thoughts onto something else preferably neutral) It takes a bit of a practice and as you start to be in control of your mentation, you'd become in control of your emotions as a result. In addition to redirecting your thoughts, you may decide to do something or phone a family member or a friend.
As far as making time go by fast, that would seem to be going faster if your time is occupied with doing things. You may decide to make something for. If she's at this camp, you can make a mug of your images at the local pharmacy (something she can bring with her when she goes back) and each time she uses it, think about the two of you. You can also make her some cookies or brownies (easy using the premade frozen ones from the store and just bake) and put them in a nice tin for her. She may feel lonely at the camp and if you think of anything that she may bring to make her time more enjoyable, you can get that for her in a little gift package (magazines, mp3, a book, scented candle, etc)