Why is FB official even a thing or important especially at your ages? Who cares -- as long as all your real life friends and family know you are in a relationship who cares what random online people that you probably barely ever socialize with think? Just ask her when in her presence and do it while with her if it's something important to you, or her.
Life is a song - sing it. Life is a game - play it. Life is a challenge - meet it. Life is a dream - realize it. Life is a sacrifice - offer it. Life is love - enjoy it.