I'm sorry to say that unless the perp turns themselves in, this isn't going to have a happy ending. What is important now is that you realize that you've survived a quite traumatic event in your life. Carry that thought with you always. You will need to talk with a therapist as soon as possible.
NOT YOUR FAULT, but its too late to PROVE anything now. learn to not go places by yourself (unfortunately there's alot of sick people out there) and look into purchasing pepper spray for your key chain. ask police officer.