Relationship question?

I've been talking to a girl for close to 6 months. She was really into me (admitted that she liked me since middle school). I'm a shy guy and never told her how much i liked her. She mentioned dating multiple times but i wasnt comfortable asking her to date. A couple days ago i mustered up some courage and she said " i dont know, i dont realy want to."

We still talk in school occasionally and she smiles at me when we pass in the hall. I really want to tell this girl how i feel about her but i think it may be too late for that. Any advise?