B.M.
Hi D.,
I do agree with the first post about feeding more during the day and see if that helps.
I do have to say though that sometimes babies just don't have the "maturity" to sleep through the night at 4 months. Some kids are just better sleepers than others. I don't know that I agree with the withholding food at night unless you know FOR SURE that she is not hungry. It is definately a personal choice as to how you deal with sleep issues.
I have 2 boys and one was a preemie and he slept well (too well) and my 11 month old who still doesn't sleep through the night on a consistant basis.
I wish you luck. I feel your pain of not getting a full night's sleep!
B.