if i were you, I would go to the store and try them on.
The problem with UGGs is that they are kind of UGGly and if you get them too large, they are going to look ridiculous on your feet (like wearing Conan the Barbarian boots)
Plus, I only saw a handful of girls wear them this year. They are not very fashionable....and with Spring coming up, they're going to look ridiculous if you wear them outside...or inside