Kammay,
I believe how we place the pump is important. Just like today, I can pump out 9.5 oz because of the reflex at the side of the electric pump. I then tried hard to press the Avent manual pump. I got 5 oz at this side. Finally, I used my hand as well.
I think that there is a position that stimilate much milk flow, just like when our bbs are sucking
I discovered that there would be occasions which I could not express the milk, though I could feel that there was still plenty inside! I've found out that there is a certain point at which you can have 酸軟 feeling (reflex 反射反應), just like when you are feeding your bb. Much more milk will come out.
I am now using Medela minielectric and Avent manual at the same time. So, when the side of Medela has induced the reflex, I'll try to pump more frequently the Avent side. Stick to that position until no more milk come out. IN the past I moved from here to there and could not sustain the pressure. Lesser milk could be expressed!