motherearth - gonna have to correct you about the charts, and regular MN people will know I have a bee in my bonnet about this, sorry
The charts in use in the UK are not based on formula fed babies (unless your area is using something very strange). They are based on many thousands of UK babies, whose feeding is not differentiated. Some of the babies will have been excl bf, some will have been mixed fed, some will have been formula fed, some will have had early solids. The charts are called 'UK 90' and they should be ID'd as such in the parentheld child health record. They have been in widespread use since the early 90s. Earlier charts were also based on UK babies, with non-differentiated feeding.
In any case, in the first weeks a well-fed breastfed baby typically gains weight a little faster than a formula fed baby. After the first months, a gap starts to appear, when bf seems to make babies slightly lighter than formula feds.
It is also not normal at all for a breastfed baby to go several days between poos - that is a red flag that shows other aspects of the baby's health need looking at, especially the feeding. Several days between poos is only normal after the first four weeks or so. Very occasionally, a healthy bf baby where the feeding is going well will miss a day or so - this is not the case with bamboo's baby, who has not reached birthweight yet and has actually lost weight since the last weighing (not sure where you read the baby had regained birthweight - sorry if I have missed it). The baby is also very sleepy. So the lack of poos, the poor feeding experience, the baby's behaviour and the slow weight gain/weight loss is all part of the same picture.
I am very sad for bamboo, but glad she is getting some expert help, and agree with mears that this is well-overdue and that the infant feeding adviser at the hosp (if there is one) will be a good resource.
I am sure you meant to help, motherearth, but the reassurance you wanted to offer was just not right....sorry to be so blunt.