Okie dokie...I've got a (6-7mm) stacked septum, and I love it !
First... check out this info.
Now that you understand what will happen, do you stick with single pieces of jewelry, or do you like stacking better?
If you want a basic, smaller diameter, 6g ring, I have some of these that I like.
If you are wanting to stick to stacking, these 16g and 14g are awesome. And you can easily add more detailed rings to the stack.
Good luck!