Kate Middleton's Expecting!?

Kate Middleton may have had her eyes on the game when she and hubby Prince ­William ­attended a volleyball tournament in Canada at the University of British ­Columbia Okanagan on Sept. 27 — but her mind seemed to be elsewhere. The mother of two, 34, rested her hand across her gently ­blossoming belly and seemed to be musing on the big news that she's ­expecting a girl!

"Kate and William have been ­actively trying for another little one, and all the signs are there that she's pregnant," a royal source tells OK!. "Now palace insiders are buzzing about the baby's gender. Everyone is convinced it's a girl, because even though her bump is still small, Kate ­appears to be carrying high, a sure sign."

During the Canada trip with children George, 3, and Charlotte, 17 months, Kate exuded health, vigor and excitement. "So far the terrible morning sickness she endured the other two times hasn't been an issue," the insider says. "She's banned caffeine and alcohol — even her evening sherry — and she's taking it easy." And the source adds that William, 34, is making sure she doesn't overdo it: "He won't let her lift a finger!"

Now the big question is, do George and Charlotte know they're about to have a little sister join the family? Stay tuned!