The Kardashian dynasty is gaining a princess! Rob Kardashian, 29, and fiancée Blac Chyna, 28, are expecting a girl, according to a source close to the pair. “Rob couldn’t be happier,” says a Kardashian insider. And with just three months until the October due date, he and Chyna, mom of son King Cairo, 3 (with rapper ex Tyga, 26), are preparing for their daughter’s arrival, the source confirms. They have debated getting a baby nurse and planned an “over-the-top extravagant” nursery at Kardashian’s $2.2 million Calabasas, California, home, says a family source. All the while, cameras have trailed the stars of E!’s upcoming docuseries Rob & Chyna. “Everything,” says a source, “will be on the show.” UNITED FRONT Expect to see a family in harmony. Since learning he’ll be a…
