Just wanted to let you know that dd took 4 full weeks to reach her birth weight, and was never even thought to be FTT. My theory is that I was given SO much IV fluid that she came out carrying a lot of water weight, and peed it all out first chance she got. She dropped from 8lb.7oz at birth to 7lb.15oz leaving the hospital.
She nursed and nursed, although she was somewhat lazy at the breast. As long as she was happy, healthy, hydrated, having sufficient #s of poopy and wet diapers, I did not worry. I had to argue a lot with the NP (woman) who wanted me pumping and supplementing with pumped milk or formula. Finally the doc (man) intervened and said, just nurse. She (dd) obviously knows better than we do what she needs.
She is 4 and weighs 30 pounds. Her weight has always been down around 6th percentile, while her height is at 90th. As I told them from day, she is built like her Dad (6'1" and 165 lbs.), and has his metabolism.
Just another experience for you to consider. I agree w/others, to quit pumping and supplementing, and just nurse. There are always babies that wreck the curve!!
Good luck to the mama