If you love where you are now and what you are doing, I don't think you should feel pressured to change. It might be helpful to identify *what* you like so much about what you are doing now.

Your supervisor wanting to promote you is a good thing, even if it is annoying and unwanted at the moment. If you could explain to him why you like what you are doing now, he might have some ideas about how you could have those same qualities in a different job... or he may realize that you are truly happy where you are now and leave you alone!