Now that Blake Shelton and Gwen Stefani are officially husband and wife, they are putting all of their energy into growing their brood. “The wedding was more of a formality than anything else,” a source tells Us, noting that the newlyweds already feel like they’ve been married for years. “Next it’s full steam ahead for a baby.” Though he doesn’t have any children of his own, Shelton, 45, has had plenty of practice with Stefani’s kids Kingston, 15, Zuma, 12, and Apollo, 7 (with ex Gavin Rossdale), who he’s welcomed into his life with loving, open arms. “He’s a great father figure to Gwen’s boys, but there’s a sudden sense of longing to have a family of his own,” shares the source, adding that Stefani, 51, had previously chosen a surrogate…