Be different and be happy!
My mother dressed us the same and she never covered up my birthmark as a child and today I still do not. I am not ashamed of it. It is part of me. What you see is what you get.
When I am out I see people stare at me then look at my face, I think I must have a dirty mark or maybe my dress is caught up in my knickers. Then I realise they are looking at my birthmark but at least they are looking at me.
I feel that sometimes this is an advantage as I do get noticed.