I'll second (or is it third) that break-ups do indeed suck. But they can be blessings in disguise as well, you said it yourself, you are not the person you were when you were first together. I am sure that it is the same thing for everyone, growing up changes people. I don't know anyone who stayed the same from age 18-22. I'll be willing to bet that she has changed too. Love her all you want, trust me, it takes two people to make a relationship work. Which is the same reason Jennifer Tilly won't return any of my letters.... but that is a different story.
Let her be, it's up to you when you are gonna cut your losses and move on, but if you really want to make it work (which never works btw) don't creep her out by stalking her and forcing her to make anymore rash decisions. you won't like the outcome.