I think it's mental. I cannot get any milk by pumping unless I start thinking really tender, milky thoughts. Have to look at pictures of babies, especially my baby, concentrate on her mouth, think of how my body is feeding her, milky, milky, milky...then it comes! Also, I had to turn the pump on MUCH slower than I would have expected in order to get good streams of milk. (Or go much slower with the hand pump, as I have used both.)
Homeschooling mama to DD 3/28/06 , DS 2/27/10 , Belle the Orange Dog 03/11, and DD 10/03/2013.