Jill Duggar tells Us Weekly that she was "very surprised" to learn that she was expecting her first child with Derick Dillard — the story behind how she discovered her pregnancy! Credit: Courtesy of TLC

Third time's a charm! Jill Duggar tells Us Weekly that she was "very surprised" to learn last month that she was expecting her first child with husband Derick Dillard. The 19 Kids and Counting star recently opened up to Us about her pregnancy, recalling the very moment she realized she would be a mom and how her husband has been taking care of her.

"I was thinking that maybe we should take a pregnancy test," recalls the TLC star, 23, whose period was noticeably late. She began with two pregnancy tests that "were both negative" she says. When the results for test number three arrived, the newlyweds were shocked.

"We were really surprised when we got that positive test," Duggar says, "but of course we were really excited. I think we would have even been less surprised had it come back positive on one of the first tests."

Which family member convinced Duggar to take the third test? "It was Jinger," Jill tells Us of one of her eight younger sisters, 20, who was the first person to learn of her pregnancy. "She was like, 'You know, mama has a bunch of pregnancy tests upstairs. You should take one of hers.'" Jill laughed at the idea, but took one in her parents' bathroom to prove her sisters wrong. "That's where we took one of my mom's pregnancy tests," she tells Us, "and it came back positive."

Her husband Derick was also present when Jill took the test. "Absolutely, he was there," she tells Us. "He was thrilled."

The couple dealt with some confusion initially after Jill's test returned positive. "One of the [previous] pregnancy tests had the little plus sign and the other one had the straight line. The one we had taken two days before was the one that was supposed to have the plus sign. The one I took at my mom's was just one line." Laughing, Duggar says her husband saw the line on her third and final test and said: "No babe. Look! You're not pregnant.'"

But she was! "We were super excited," Duggar says. "We prayed together, and thanked God for this new little life. I was screaming and everything," she laughs. "He was like, 'Don't get too excited! You might stress out the baby or something.' He's so cute. He's so sweet."

In the flurry of their excitement, the couple left the empty pregnancy test in Michelle and Jim Bob's bathroom. "My mom texted me later inquiring about it. She was like, 'So I have a question! I found an empty pregnancy test in the trash can and your cup on the counter, so anything you want to share?'" Jill wanted to wait to see her parents face-to-face to reveal her happy news. "I was like, 'We'll wait and see,'" Duggar recalls. "It was funny. She had a suspicion there. She was thinking, 'something's up.'"

Duggar confirmed to Us on Aug. 20 that she was indeed expecting her first child, 60 days after their wedding. She tells Us, "We really didn’t know how long we’d be able to keep it a secret with all of our friends. We wanted to tell them."

Many fans were surprised that Duggar disclosed the baby news so early on in the pregnancy; most miscarriages happen within the first trimester. But the devout Christian couple still wanted to share their news. "Believing that life begins at conception and that every life is precious no matter how young, we would — even if there were to be a miscarriage — we would still want that child to be recognized," she tells Us. "So it was something that we thought about and went forward with."

Tune in to the new season of TLC's 19 Kids and Counting on Tuesdays at 9 p.m. ET.