Hey - I went through something very similar with my college girl friend. I didn't buy the ring, and I'm glad I didn't. Once we were out on our own, away from college, I realized that during college we were great for each other, after that, not so much. Haven't seen here in 10 years. Haven't missed her. I met my wife 9 years ago.

Just a thought, don't rush into it. You have a lot going on and there is no reason to add to it.

If you feel you need to give her something, I recommend following Cinda's advice.