"When I look at her my heart melts," Simpson, the pop star-turned-fashion designer, said in an interview appearing in the June issue of People magazine. "I didn't realize how much love I could have."
Maxwell, known as "Max" or "Maxi," arrived two weeks early, by C-section. She weighed 9 pounds, 13 ounces.
"As one of the nurses exclaimed when Max was born, 'She's a chunk,'" People magazine's Suzanne Zuckerman told " Good Morning America." "But she is a beautiful baby.
"There was a wonderful family bond that was instantaneous," Zuckerman said. "As Max was being born, Eric was holding both Jessica's hand and the baby's hand so there was that sort of continuous bond from the moment she arrived."
Maxwell has Simpson up every few hours for feedings and diaper changes, even though her father, former NFL player Eric Johnson, is a very hands-on dad.
"He has found his calling," Simpson said of her fiancé. "Maxwell's definitely going to be a daddy's girl."
Maxwell "is my career at the moment. I know I was always meant to be a mom …," Simpson, 31, told People.
"She says that she's never before kept to such a schedule in her life," Zuckerman said. "What's also remarkable is this confidence that's just bubbling over with Jessica. When it comes to being a mom, she fully admits she's doing a fantastic job."
During the revealing interview, Simpson, who was criticized for gaining too much weight during her pregnancy, also discussed her plans for losing weight.
The new mother is adding to her coffers with a reported $3 million deal from Weight Watchers to lose the baby weight.
"Jessica actually planned to work with Weight Watchers even before she knew she was expecting but she is committing to that program as soon as its healthy for her to do so," People's Zuckerman told "GMA."
"It would be nice to feel comfortable in a bikini, but that's not my goal," Simpson says in People. "I just want to fit into jeans."
She said she's putting off exercising until she fully recovers from the surgery, but laughingly admitted she had broken one rule. "I think I have the sexiest man in the world. So that's the rule I break."
She also acknowledged that she's eager to get back to her pre-baby weight.
"After you have your baby, it's like, 'Oh my God, what happened to my body?' This is not me,'" she said.
The singer has big plans for her wedding to Johnson, and says she wants to feel "really great in a wedding dress."
Simpson will launch a new maternity clothing line that will be the 24th line in the Jessica Simpson Collection. The singer is well on her way to earning $1 billion by year's end just from her fashion empire alone.
"She'd love to have more kids although she very openly says she wants to devote her full time and attention to Max right now, so no immediate plans," Zuckerman said.