Good advice from everyone so I won't repeat most of it but most important aspect is she IS gaining weight. She was born at a weight that was in the 90th percentile. She will likely not remain in that percentile, esp if she's BFed baby, so you might find she's evening out.

For the MCHN to expect her to 'hit' her birthweight in a week seems like so much pressure on you and on J to conform, when babies don't always conform. She's gaining, and gaining a decent amount, and while it might not mean she stays in the 90th percentile, if she is otherwise happy, I'd give both you and her some leeway and she will hit her birthweight sometime before she's 4 weeks. And you know what? She'll still be heavier than Charlie was at that age.