My LO is 3 1/2 mos, I will be going back to work in about 3 weeks. I had pumped and built up a good freezer supply of milk, but found out 2 weeks ago that he has a milk allergy. Therefore, most of the milk I have in the freezer he can't tolerate (develops severe colic) . I know I will need a good supply of frozen milk to help supplement what I will be able to pump at work, I just don't know how much is enough. I will be working only 2 days a week, but the shifts are long (about 12 hours).