The only way for her to know how you feel about her is for you to tell her. I’m not saying that you need to walk right up to her and declare your love right out of the blue. It’s easier to ease into such a discussion by making contact with her and opening up a line of communication.Talk to her, ask interested questions and listen to her. In the course of conversation, you will be able to find out whether she has a boyfriend or not. If she does, then you can still be her friend and let her know that if it she finds herself available that you would like to date her.If she doesn’t have a boyfriend, then tell her what you like about her and that you want to see more of her. You sound absolutely adorable and I think that it is charming that you have liked her for so long. She will be lucky to have you.