Happy face- there’s definitely an inyan for a Kallah to be happy when it gets closer to the Chasuna. But during your entire engagement, I guess the happiness should be natural!
3 days prior to my wedding, my grandmother passed away. The Rav told us, that the Kallah should not think about the tragedy, and I shouldnt be sad. On the contrary, I should try extra hard to be happy in these few days before my wedding.