Baby not satisfied with expressed milk--advice?

huskymomma94

I have been occasionally pumping and giving DS a bottle in preparation for my return to work in a month. He takes the bottle just fine. He tries to chug it down in 5 minutes...we try to draw it out to mimic the length of a breastfeeding session, but I'm not quite sure how to do this since he starts crying when we take the bottle away. Anyway, the problem is after the bottle is finished--DS is NOT satisfied and starts screaming. I really don't think its hunger, because it happens no matter how much milk we give him. Our breastfeeding sessions usually last about 20-30 minutes and I think he is used to controlling when we are finished.  Any advice?