babies that are slower in gross motor skills often shine in other ways.
she may be a very crafty little thing, to clever for her own good, knowing that people will come to her, bring her things & pick her up, so why walk. I think it's common for #2 to do that esp when their sibling brings them toys etc

my ds crawled & walked much longer after others his age, but man this kid has the memory of an elephant and shocks people with how articulate he is.