From PEOPLE Magazine Click to enlarge
As Celine Dion was packing her family's bags for a vacation one morning last December, her fertility doctor called her Florida home with her latest test results. But, watching as her husband of 15 years, René Angélil, broke down in tears, she knew it wasn't the news they had hoped for. She wasn't pregnant; her fourth IVF attempt had failed.

Dion was devastated, but given that her son, 9-year-old René-Charles, was downstairs waiting to leave for Disney World, the singer had to keep her feelings in check. "I didn't want to get into the emotion—it wasn't time to cry about something that didn't work," she recalls. Instead she reached for a silver lining: "I said to him, 'The bad news is Mommy isn't pregnant. But the good news is I'm going to be able to go on every ride with you!' And I did. We had a ball."

Almost two months later Dion is preparing to take another roller-coaster ride. Her film Celine: Through the Eyes of the World, which documents her recent yearlong 132-date tour, hits theaters Feb. 17, and she'll kick off a new Las Vegas show in 2011. As her career moves on, she has also decided to give her dream of a second baby another chance. "Not like forever, 17 times," says Dion. But "I'm going to try until it works."

In January Dion, 41, began the grueling process of preparing her body for her fifth IVF attempt in six months: estrogen patches, blood tests every other day ("Your veins get weak"), frequent ultrasounds and daily hormone injections. "It's not, 'Oh, poor Celine,' but it's a lot," she says, touching her bruised thighs, which are numb and full of lumps from the long needles that go deep into the muscle. "I give the shots to myself. But René's with me." The hormones that help make a pregnancy possible also bring a tidal wave of emotions; sometimes Dion cries for no reason at all. "We go crazy waiting for the results," says Angélil, 68. "It's like waiting for the lotto, but it's bigger than that—imagine. It's the biggest news you can get." Says Dion: "You do everything [right], and you're careful, and you rest, and then ..."

Her first IVF attempt in August, in fact, seemed to work. News of her pregnancy leaked to the press, so Dion felt an obligation to her fans to confirm it, only to lose the pregnancy days later. She and Angélil decided to try again the next month. "Everybody's calling to congratulate me, they're sending balloons and gifts, and I don't return their calls to thank them. How do I do that?" she says. "I felt bad because I was not pregnant."

Nor is her struggle easy for Dion to explain to her son, whom she calls R.C. "He said, 'Wasn't it supposed to be 100 percent?'" she says. "I said, 'It's like nature, a little flower grows and then too much wind and then ... [But] another one's going to grow.'"

The couple's second and third procedures last fall were also unsuccessful, and with a new Vegas show deal in the works by then, Dion thought their fourth round of IVF in December would be their last. Learning that it had also failed felt like "an end to motherhood. I found it really hard," says the singer, who grew up with 13 siblings. So when Angélil—who says they're "not really" considering adoption—told her over the holidays that he wanted to try again, she was overjoyed. "There's something inside of me that says [not to] give myself that pressure, that it's my last time," she says, adding that doctors say they were "extremely lucky" to become pregnant with R.C. on their first IVF try 10 years ago and that four or five attempts are not uncommon for couples with fertility issues. "She knows a lot of women have this problem," says her sister Manon, 49. Adds Dion: "We would love to expand our family. But honestly I'm more than blessed with my son. He is everything for me."

So much so that the world's top earner in album and concert sales for the last decade wakes up at the very un-showbiz hour of 6:30 a.m. every weekday to drive her son to "his first normal school" (he was home-schooled in Las Vegas and on her world tour) 10 minutes from their home in Jupiter, Fla. When R.C. isn't manipulating music on his computer or deejay table ("Rihanna's big-time in our house," she says), he's playing golf, basketball and, more recently, baseball and soccer. The second grader is sleeping in his parents' bed (along with the family's 5-month-old female yellow Lab, Charlie) while he adjusts to his new surroundings after living on the road for so long. "I'm more than fine with it," says Dion. "I have my two boys with me, the dog that snores, a fish tank that bubbles, the pet rat Lionel that scratches—everybody's with Mommy! There's a lot of action!" she laughs. "It's not about beauty sleep anymore. When they're not there, you miss it so much."

That's why Angélil, who's also her manager, scheduled Dion's upcoming Vegas show—which will include favorites from her own repertoire plus hit movie songs—around their son's school schedule. The Caesars Palace residency will launch March 15, 2011, with or without a baby in tow, and will include about 70 performances a year. Says Dion: "I'll balance my showbiz life with my most important job: motherhood."

To that end, she's hoping the fifth IVF try's the charm. "We tell her, 'Cross your fingers—and your legs!'" says her sister Manon. Plus, "Five's my lucky number, so this is the time it's got to [work]," says Dion. "We would love for my son to have a brother or sister—no rats, no dogs, no fish can replace that, you know? But you don't control. It's up to God.... One way or another we're going to be good."