Hi L.,
Can you pump when you first wake in the morning or after the first morning feeding and give her that milk at night? After a few days of pumping you might start making more milk and will have more milk for the evening feed or to store for another day. If she seems to be eating less, it might be because your mother's milk changes in nutrients and caloric levels as she grows and she might be getting what she needs with less nursing.
In response to some of the posts you've received I have to stick up for babies and for development of their self-esteem and say babies are smart little human organisms. Their internal impulses (like saying yes or no to a certain food) are an important way through which they come to know who they are. When they're forced to do something that is out of synch with their internal impulses, the message that is sent is that who they know themselves to be is wrong. Forcing a baby to get too hungry to follow her/his own sense of what is right and wrong for them is cruel and demeaning. I hope you don't mind my pulling out my soap box to speak to the community on your post.
I hope you can pump enough or find a formula that she likes to solve your problem!
Best of luck to you,
K.