The star welcomed her third child on March 19.

By Jen Juneau
May 08, 2019

is basking in the glow of her new-mom achievements!

The singer, actress and businesswoman couldn’t resist showing off the fruits of her pumping labor on Instagram Tuesday, of a full 5 oz. bottle of breast milk for her 2-week-old daughter .

“This is what success feels like,” wrote Simpson, 38, adding a cow emoji.

The star welcomed her third child with husband on March 19. She joins the couple’s son , 5½, and daughter , 7 next month.

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Simpson couldn’t be more excited about the new addition to her family. And now, with the pregnancy behind her, the mother of three is keeping positive as she .

“She had the best attitude about her recovery,” an insider previously told PEOPLE. “She was very excited . Her older kids were around [the hospital] a lot and doted on the baby.”

Though a close friend of Simpson recently joked to PEOPLE that Maxwell (who weighed 9 lbs., 13 oz., at birth) was “hoping to maintain her record of the biggest baby in the family,” Birdie had her big sister beat as she .

Regardless, the pal added that Maxwell is “so in love with her little sister” — as is big brother Ace — raving, “They can’t get enough of the baby. Everyone is very happy.”

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Despite woes from severe acid reflux  to sciatica and  during her pregnancy, Simpson still remained active in her older kids’ lives while awaiting Birdie’s arrival.

“Jessica loves being a mom and having a big family,” said another source. “Even , she volunteered at her kids’ school. Her life is very focused on her family and making it fun for the kids.”

In the days since giving birth to baby Birdie, Simpson’s friend told PEOPLE the former star has been “feeling good.”

“The baby is doing really well,” added the pal. “Birdie is perfect, and . Her family has been back to visit at the hospital and they are elated. They are just soaking it all in.”

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