i have already asked a question and tried to express my gran

i have already asked a question and tried to express my granddaughters bladder, but she is only a month old, i forgot to say this in the question, she does not understand that she has to let us press on bladder, she riggles all the time, so as we go to press her tummy she moves and will not stay still, sorry to ask again please help, i have contacted the doctor and he said just carry on trying to express her bladder but surely that is not doing her any good because of not being able to empty it at all.