Recently my dh and I did a workshop with Aletha Solter (Aware Parenting Institute) who is one of the best authors on child-rearing I've read. AwareParenting.com
(The workshop was sponsored by API of San Francisco.) She talked about the disservice we do to our child (she granted that some consider this idea controversial) by always passifying the crying and said she sees the breast often used as a passifier. (DH and I came away from the workshop nodding our heads at how we did this in the past--now ds is 2.5 and weaned.) It is painful to hear our babies cry, but sometimes that may be what they are needing, as a means of resolving tension they hold from past traumas (whether or not you can identify them.) Might be birth trauma, intrauterine trauma, even an unconscious awareness of the war and world tensions, or something that happened that very day. You might like her book Aware Baby. She did specifically respond to a question about nighttime nursing, and thought that toddlers still waking multiple times are probably needing to cry more than to nurse.
Oh yes, then you have the crying. It's so hard in the middle of the night when you are so tired and the breast is so convenient...but what would be best is to hold your child through the crying in a loving way, giving the message (non-verbal may be fine) that you welcome the crying as a way to work through some held pain, supporting her process.
It is so important that you take care of yourself. In the big picture everyone benefits most optimally with you well cared for.
When we did finally night-wean, I couldn't follow Dr. Jay through--no alarm setting for me! We did have to allow for crying--but it is so different from CIO when you are right there with loving arms. I often asked if he wanted some soy milk or cows milk and sometimes it was yes, sometimes no. (Even then the milk may have been more of a comfort than real hunger, as eventually he was sleeping through the night.)
Good luck. Middle of the night transitions are sooooo difficult, but I found it so liberating too. We had put ds in his own room at 18months, which I am grateful for, as we needed it, but now at 2.5 he somehow ended up back in our bed, and we love his company. No resentment at all.