bf help for women with large breasts

Is there something special that a woman with large breasts needs to be aware
of when breastfeeding? I am having a lot of trouble with my 4 week old.
I've had to supplement since day 5, and I want to stop but she is always
hungry, so I keep having to give her formula, about 6 ounces a day! I am
sure she's getting some milk, but my Ameda Purely Yours pump gets just a
trickle out of me when I try to pump. I have to go back to work in a few
weeks so pumping is important. I've been to the LCs twice and they say
things are fine but that is under intense, controlled conditions. I've been
having to nurse her every hour during the day....she sleeps well at night
and I've been told not to wake her up so I don't, but she goes 4-6 hours
without eating at night.

Alberta