pumping question

Krisnralph

I am now back to work and have been reading all the wonderful post on here to help me.  I keep reading about getting a 2nd or 3rd letdown.  I keep seeing people say they get their 2nd letdown at about 20 minutes. I don't feel any let down so I pump for atleast 20 minutes.  I am only getting about 2 oz on one side and 1 oz on the other side.  I have been reading about people getting alot more per pumping session. Is there anything I can do to get more milk output?  Should I be pumping longer?  When I reach 20 minutes I do not see any milk coming out.  My DS is taking about 12 oz at DC per day, he is there around 9-10 hours a day. 

Thanks for the help in advance!