I remember thinking the same way you are, in fact, I thought this way until I was well into my 20's. I have had many relationships something like the one you are describing, but this was before I was saved and found out what the Bible has to say on the issue.
I have to tell ya, I agree with those here who believe in not dating. When you look at the examples in the Bible, you don't find couples dating. What you do find is a man and a woman meeting, deciding they are for each other, and coming together in marriage. In fact, in one case, it wasn't even this. Abraham sent a servant to find a wife for his son Isaac. There are no instances of dating in the Bible, only courtship, which is much different. From what I understand, courtship is more of an examination, a deep exchange that had nothing to do with infatuation, and everything to do with carefully weighing whether or not two people are ment for each other. It has very little to do with love, but God should be in every inch and fibre of it.
Some dangers to watch out for. First, if you are focusing more on her than you are focusing on what God wants, then this is Idolatry and needs to be stopped. I'm not saying it to be harsh or mean, but it is doctrine. If we put anything between us and God, whether it be a job, a car, a man or woman, a hobby, it is Idolatry.
Exodus 20:3 Thou shalt have no other gods before me.
Our focus needs to be on God, as so many have already said here.
The point I am trying to get to in a round about way, is that God is God, he is perfect, and he knows what he is doing. We need to trust him in all things, even for a wife. I would put the dating thing on hiatus. Let her know that your feelings haven't changed, but you just want to do as God would have you do. Besides, there is no rush. That was the biggest lesson I had to learn. This idea that you have to be married by a certain age is ludicrous. When you look at Jesus in the Bible, was he ever in a rush? Was he sprinting across the water, or walking?
I understand that you feel a certain way about this girl, but you can't let your emotions control you. Commit it to prayer, but remember that God's answer to prayer will never contradict His Word.