How can I get her to come back?

[Sage]

Sadly it doesn't matter how much effort you put into this & what she might be missing out on. She has told you clearly and quite carefully that she doesn't want to meet you and wants to end your contact.You have to respect her wishes, even though you would like things to be different. You are likely to be going to university in the future and her life will be moving on as well. I think it might help you in your next relationship if you try not to be so intense and committed and try to pick up the signs if the relationship is coming to a natural conclusion - this girl was giving clear signs before she made the final break.