my son is almost 5 months old. i seem to only be able to pump 4 oz per session every 3.5 hours when i am away. this is the same amount i've been pumping since he was born. my child care is saying that he seems to continue to be hungry after he drinks 4 oz so i told her to give him 4.5-5oz. is this normal to not increase pump out take as child grows? will i ever begin pumping more?