How long are your pumping sessions at work? I have been struggling with low supply issues, and at home have been pumping for an hour at a time several times a day just to get enough to provide one 5-oz bottle for each of my twins each day. I really can't afford for my supply to decrease, but I also doubt I'll be able to pump for an hour at a time at work. What should I shoot for? 20 minutes? 30? Is there some optimum length of time?
(I also asked this over on Working Moms, but I'd like to hear from the knowledgeable ladies here, too!)