Is a fourth royal baby on the way? People who know Kate Middleton sure think so! "Those close to Kate are saying she's pregnant with baby No. 4!" a source revealed. "Kate is showing all the signs of pregnancy."

Kate and her husband, Prince William, welcomed their third child, son Prince Louis, on April 23, and their two older kids, Prince George, 4, and Princess Charlotte, 3, are adjusting to life with their new sibling very well. That said, her cutest helpers undoubtedly will be George and Charlotte (when they’re not being a handful themselves, that is!).

"George loves boasting to friends that he’s a big brother," a source told Life & Style. "And he is extremely protective over Louis. He’s even been known to sneak out of bed at night so that he can fall asleep in the nursery next to his baby brother."

At first, Charlotte "was slightly jealous of Louis since she loves to be the center of attention," the source notes. "But now she’s gotten used to him being around and treats him like a little doll."

With her kids adapting so well to Louis, the source adds, "Kate and William are confident that having another baby won’t be an issue" for their little ones. It’s certainly not an issue for the proud parents-to-be. "It is fantastic having a lovely little family and I am so thrilled," raves William. "Catherine has been doing an amazing job as a mother and I’m very proud of her."

prince louis

The couple — who previously wed in April 2011 — have also always talked about having a lot of kids. "She and William have always said they wanted four children to complete their family," the insider shared. "Actually, William would like to have five kids — but Kate thinks four is enough!" We are hoping for six!