KT4 - you need to see a lactation consultant! Tell me, how many breastfeeds does she have in 24 hours? Both sides? or just one? What have her wet and dirty nappies been like (colour/quantitiy - esp poo) What kind of pump do you have? How was the birth? Do you have any pre-existing medical conditions?
You need a hand there. If you tell me where you live I could suggest some-one - PM me if you like!)