If she is broody, she will stay in the nest night and day. If you approach her, she will likely growl and peck at you.. If you lift her out of the nest (you might want to wear gloves,) she will probably fluff out and squat, as well as growl.
If she is really broody, then yes, she might very well hatch your eggs. But understand that sometimes they stop being broody before the eggs are hatched, and this may be more likely with such a young one.
I've decided to give Amy a chance at hatching some chicks ....I have got some "maybe" fertilised eggs from a farmer and put them under her today , I have separated her from the other girls and just see what happens . I have never done this before so all advise will be more than welcome x x