I read most of everyone's replies and think everyone is overanalyzing. Hey, Rocketboy, the true for every relationship is that they most evolve, sometimes they just get caught on tecnicalities and die off. That's something you must understand. By the way, when i mean evolve is move to the next step (more commitment, and the final step being marriage).
Here's some general advice by me:
1) Don't take advice about relationships in your youth from girls (no matter their age)
2) Don't bother yourself about escalating relationship-wise. Men escalate physically (make her feel comfortable, create a connection, etc...). Therefore, you agree to get in a relationship only if you feel like it.
3) Be prepared for relationships to end (relationships go forward, and if they can't go on, they will die). You don't know when it's going to happen, but it will happen!. Frankly, what i do to ease the pain, it's to always keep some possible girls around and definately have fun with your buddies.
4) Always look your best (workout, dress with your own style, etc...). Focus on the big triangle (Wealth, Health and Happiness)
For your relationship:
Well, i still stand by 50-50. It means you've to let her chase. Anyway here what i will do in your case. I will go to her and tell her:
"You know I've been thinking recently about us, about our relationship, about what's to come. I know what we have is like a beautiful spark that keeps on shining. I know we should fight for this, fight to keep this special love we have for each other. Trust me, no matter what's to come, our love will survive." or something like these, be careful with what you say, you don't want to make it look, like you'll wait around for her forever.
After you say something along those lines in a comfortable setting (a surprise outing, perhaps?), break contact with her (let her think things throught, and then make a decision). She knows your stance. Well, Good luck.
zoobyshoe said:
If you somehow patch it up with her, I'm saying, things will end the same way unless something is different. This could well be the thing she wanted to be different. Alot of young girls can't express this too directly and expect you to be sensitive to their less direct green lights. It seems to me that kissing you and saying you were the best was a kind of blanket green light. She was probably giving you permission to proceed, without discussion, unless or until she put up a red light. Her initial, verbal "I'm not ready," isn't something you can always expect to be overturned by a direct, verbal "I'm ready." The "I'm ready" comes in the form of favorable responses to escalations in physical intimacy on your part.
I like zoobyshoe's thinking. That's why men's focus is escalating physically. You don't choose to stop, she does, and it doesn't mean you can't escalate later on (be seconds, minutes, hours or days). Don't wait too long. Also, remember never force her, just be smooth.
Here's something that works for me. It's called the two forward and one backwards. When you're "escalating", and she blocks you (grabs your hands, push them away, etc...) you go back to what she was letting you do, give it a couple minutes, and proceed not to where you were at, but the next place on the list.
But in hindsight, I'm brilliant. 
trouble at the mo' but that's life for you 
Do you realize how completely patronizing you're sounding?
