The newly-engaged couple Prince Harry and Meghan Markle are gearing up for their big royal wedding! For their most recent photo shoot, Meghan wore a $75,000 Ralph & Russo gown (what a nice gift). On top of that, the royal family will pay for the wedding, says the prince’s rep, Jason Knauf, adding that Harry and Meghan “also want… the public to feel part of the celebrations.”

But Meghan has no time to waste. With her and Harry’s May 19 wedding date quickly approaching, “she’s working around the clock to plan everything,” an insider told In Touch. “But with such little time to organize the most talked-about wedding of the year, Meghan is feeling overwhelmed.”

Who could blame her? This, of course, is no ordinary affair. From the dress, jewels, and reception to the bridal party and growing guest list, every decision Meghan, 36, and Harry, 33, make will be scrutinized. And while she and Harry are “leading the planning process,” says his communications secretary, Jason Knauf, they’ve also hired a top wedding planner, says the insider. Soon-to-be sister-in-law Kate Middleton, “who’s been a calming influence, is also helping Meghan organize things,” adds the insider. And though they will be respectful of tradition, Knauf promises that “the wedding will be a moment of fun and joy that will reflect the characters of the bride and groom.”

Perhaps the biggest decision is what the divorcée will wear. “Meghan has asked some of her favorite designers, including Inbal Dror, Erdem, and Misha Nonoo, to draw up wedding dress sketches,” reveals the insider. “She wants something long that covers her shoulders with lace detailing and a sexy edge to it.”

She’s debating wearing a tiara like other royal brides. “Meghan is entitled to borrow one from the family,” explains the insider. “One of her favorites is the Strathmore Rose Tiara, which belonged to the Queen Mother, but she’d also love to pay tribute to [Harry’s mother] Princess Diana by wearing one of hers.”

Harry, who was just appointed Captain General of the Royal Marines — taking over for his grandfather, Prince Philip — will likely wear a uniform, says the insider. As for the bridal party, Meghan wants Harry’s nephew and niece, Prince George and Princess Charlotte, to serve as a page boy and bridesmaid. “The children absolutely adore her,” says the insider, adding that Meghan has also tapped her best friend, stylist Jessica Mulroney, to be a bridesmaid, while Harry’s asked William to be his best man.

The wedding venue, St. George’s Chapel at Windsor Castle, can hold 800 guests. “But Meghan, who’s only inviting her most trusted family and friends so far, is having difficulty deciding who else to invite,” says the insider. “And all kinds of old friends and celebrities are crawling out of the woodwork, hoping to get on the guest list.” That includes Ivanka Trump, says the insider, who was accused of angling for an invite when she tweeted engagement well-wishes — two weeks late.

Barack Obama, however, with whom Harry’s been friendly for years, is a shoo-in for the guest list, especially since Harry recently interviewed him for BBC radio. We'll have to wait for the big day to see how everything unfolds!

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