Keep a few things in mind:
1. She just got out of a relationship, and now is not really the time for her to hop into a new one.
2. I had the same experience in high school. I didn't help the girl through a breakup, but was always just a good friend to her. It was clear that my feelings for her were not mutual, so I simply had to respect that. In doing so, I also needed to guard my heart, and not give it to her. This wasn't as easy as just flipping a switch, but it was something I needed to do for my own sake. You just have to accept it. If you do not accept this, then you can miss out on having a really good friend.
3. Sometimes it takes time for feelings to develop in a woman, but you must always make sure she feels free, and is not choosing you out of pity or because she doesn't want to hurt your feelings. Therefore, it is a good thing that she has been honest with you about her feelings (or lack thereof). It gives you the opportunity to respect that instead of wondering where she's at. If her mind changes, she'll let you know. But don't put your life on hold in the meantime. Independence is an attractive quality.
4. God has a plan for your life, so be at peace. If he is calling you to marriage, then it will be with a woman who cannot wait to be with you. You won't have to convince her of anything, because love is always free and mutual.
For ideas on how to find the right girl for you, click here.