This is not an easy situation you are in. Sometimes love make us a little weak in the knees and tongue tied. There is no right way to approach this and in the end you will need to do what is best for you, but here are some suggestions.
First, you could try to write down what you feel. When you are away from her, sometimes your thoughts will be clearer. In this way, you will be able to think and write with all the nervousness and emotions. You may even want to read what you have written to her. This might sounds unromantic, but she may appreciate all the thought you put into this.
Second, you might want to write a letter to her. A handwritten letter is charming. I've done this in the past and it worked really well. You will be surprised how much people like to get handwritten letters. In a world of emails, this is a lost art. Best of luck!