Hi.
Dying would be a high price to pay for a relationship...but I know what you mean. Becoming dependent on someone else can be scary--and yet also so secure and comfortable that people do it all the time.
The risks, of course, are that breaking up leaves you feeling empty but also that during the relationship itself you're missing out on things, because you're not allowing yourself to fully develop as an individual. Being younger, and still figuring out who you are, this a particularly important time for that.
You yourself seem pretty much on top of the situation. At least you know what the problem is. Now maybe you're ready for a little more life of your own!
This could be a good time to take up a new sport or interest, pursue a new friend, or even just go somewhere without your boyfriend. If none of that sounds like you, maybe take a class or read a book to get you started thinking. You're very clear on wanting more "independence." So the question is: What would make YOU feel more independent?
I also recommend being easy on yourself, though, and recognizing that when people become very close, there tends to be a certain amount of interdependence.