In every relationship, there is always someone who loves the other person more. Its just how it is. I dont think that you needed to break up with her, you could have had a mature discussion with her about needing to take the relationship less seriously. Your right, a serious relationship inhibits fun, especially at a young age. If she can be mature about it and see it from your perspective, I see no need to end it.
Tell her you want to continue seeing her, but things need to say pretty casual. =) GOOD LUCK!
Hunter S. Thompson once said "Buy the ticket, Take the ride."