Prince William has opened up about the struggles and joys of being a parent after losing his  mother Princess Diana when he was just 15 years old.   William, the Duke of Cambridge and his wife, Catherine, Duchess of Cambridge, are parents to Prince George, 6, Princess Charlotte, 5 and Prince Louis, 2. His mother, Princess Diana, died in a car crash in Paris in 1997.                 William while speaking to former soccer player …