So how many times do you switch her before trying to put her down? Just once (i.e. from breast A to breast B) or more than once (i.e. from breast A to breast Bm then back to A, etc.)?
Some babies never really get that "milk drunk" look. With those babies, I think it's very important to follow the baby's lead- if she seems hungry, she probably IS hungry. My first kid was that way- she was not an efficient nurser in the early weeks, and wasn't gaining weight the way she should have been, and the fact that I was nursing her all. the. time. was the only reason she didn't lose weight.
Is it possible for you to rent a professional scale? I know we're brushing up against the holiday season, but if you can get your hands on a scale it might be a good thing. It would allow you to gain a more accurate picture of what your baby is doing at the breast, and whether or not you need the pumped supplements.