How could i get people to call me by my middle name?

i absolutely LOVE my middle name! my first name.... not so much... my first is Amanda and i am only named that because my dads is Armando. i am constantly called Uh-Man-Duh and thats really annoying. plus, its SO common! i want to be called by my middle name but i dont want to offend my dad although my parents know i dont like it. im 13 and i have always been called by my first name so now is it too late to change? hope not. my middle name is Juliet which i LOVE! it isnt as common, it cant be made fun of and i think its really pretty. :) sooo what should i do? i start a new school next year too so that should make it a bit easier. but what about getting my family to call me it?