If I've been playing the flute for 3 years and am top of my section which Rubank method book should I get?

I know I don't need Elementary, but should I get intermidiate or advanced? I'm just afraid intermediate will be to easy or advanced will be to hard. I'm a pretty good player. I've made all-region (honor band) and have a range from low C- high G I can play 16th notes adn 32nd notes if I try really hard.