This is not a good test, as bottles may interfere with breastfeeding. The 5 week old is suddenly pulling away from the breast but still seems hungry. During the first few weeks of life, babies often fall asleep at the breast when the flow of milk slows down even if they have not had their fill. If this is done by bottle, a bad situation may become worse. It is generally easy to use.
Scales are all different.
We have documented significant differences from one scale to another. Weights have often been written down wrong. Many rules about weight gain are taken from observations of growth of formula feeding babies. They do not necessarily apply to breastfeeding babies. A slow start may be compensated for later, by fixing the breastfeeding .