Millie Bobby Brown has done more in her 19 years (nearly 20, HBD!) than I’m likely to do in my entire life. Actress, author, and entrepreneur, her brand, florence by mills, carries makeup, skin care, fragrance, pet products, coffee, and now, clothing. Yes, today, Brown is revealing her latest venture exclusively with ELLE.com. Brown has lived squarely in the public eye since the age of 10 when she went viral as Eleven in Stranger Things. She says that experience, of discovering her sense of style throughout adolescence, is a major reason why she wanted to launch florence by mills fashion, so that girls like her can have room to play…