I think there are some little mistakes. You should have said "twelve rotring pencils" instead of "twelve pencils".
And if you say "What, have you also done so?" it means "Ne, sen de mi öyle yaptın?". But we want "sen ne ettin öyle yaa..", so you should say something like "Oh, what have you done?"
And lastly, you should add dashes "-" at the beginning of the paragraphes (They are in the form of dialogue).