Baby losing weight at 2 months

Nary

Should I be worried? My baby started to sleep through the night from 10PM- 5:30 AM for the past 5 days. And I weighted her today, she is 4.45KG (9lb 8oz). She lost. 15kg I know it’s small but just curious if this is something I should be worried. She wets her diapers a lot and do poop every day and she only drink breast milk.