How much has she lost since birth?

“A well-nourished newborn should: ... Lose no more than 8%-10% of their birth weight in the first few days after birth, before starting to gain weight again.” American Academy of Pediatrics

“Breastfed and bottle-fed newborns typically lose weight during the first 5 days after birth. This happens as they lose excess fluid. This weight loss shouldn’t be more than 10% of their birth weight. After 1-2 weeks, most newborns weigh more than they did at birth. If you’re concerned about your newborn’s weight, talk to your GP or child and family health nurse.” Raising Children Network

“When your baby was born, their weight included excess body fluid, which they lost during their first few days. All newborns lose weight during the first 7 days. Beginning once they are about 5 days old, they should start gaining weight steadily. Then, by about 2 weeks of age, they should be back at their original birth weight. Almost all babies will have regained their birth weight by 3 weeks of age.” American Academy of Pediatrics

“Your baby gains weight steadily after the first 3 to 4 days – it's normal for babies to lose some of their birth weight in the first 3 to 4 days.” NHS

“If your baby is feeding well, they should start gaining weight steadily after the first 2 weeks (it's normal for babies to lose some of their birth weight in the first 2 weeks).” NHS Best Start in Life

“Your baby is steadily gaining weight. It is normal for breastfed babies to lose some weight in the first week following birth. However, they should be back to their birth weight by day 10 to 14 of life.” CDC

“It's normal for babies to lose some weight in the first few days after birth. Your baby will be weighed during their first 2 weeks to make sure they're regaining their birthweight. Most babies are at, or above, their birthweight by 3 weeks.” NHS

“Typically, growth spurts happen at around 7 to 10 days old and again between 3 and 6 weeks old. The average newborn gains weight at a rate of almost an ounce (28 grams) per day. They tend to grow between 1 ½ and 2 inches (3.8 to 5 cm) during this month.” American Academy of Pediatrics

“In general, babies gain between 1.5 and 2 pounds (0.7 to 0.9 kg) and grow 1 to 1.5 inches (2.5 to 4 cm) each month during this period. Their head size will increase in circumference by about a half inch (1.25 cm) each month.” American Academy of Pediatrics

“The typical 4-month-old baby should:
Slow in weight gain to about 20 grams (almost two thirds of an ounce) per day or 1 and a third pounds (600 grams) per month
Weigh 2 times more than their birth weight” MedlinePlus (NIH)

“It’s not uncommon for a baby to lose some weight immediately after birth. By the time the baby is 14 days old, the birth weight should be exceeded.
A baby usually gains about 1 ounce per day during the first six months.
In general, most babies double their birth weight by 6 months of age and triple their birth weight by 1 year.” USDA WIC Breastfeeding Support

“Soon after birth, an infant normally loses about 10% to 12% of their birth weight. By about age 2 weeks, an infant should start to gain weight and grow quickly.
By age 4 to 6 months, an infant's weight should be double their birth weight.” MedlinePlus (NIH)

“By their first birthday, the average child has tripled their birth weight and is 28 to 32 inches (71 to 81 cm) tall.” American Academy of Pediatrics

“Usually your baby will gain weight most rapidly in the first 6 months. Their rate of growth will gradually slow down as they become a toddler and are more active.” NHS

“Your baby's weight and height may not follow a centile line exactly. Their measurements may go up or down by 1 centile line, but it's less common for them to cross 2 centile lines. If this happens, talk to a health visitor, who can advise you.” NHS