feeding on demand and returning to work

klp28

I'm starting to get really worried about how my H is going to manage feeding our son when I go back to work at the end of the month.  Aside from the fact that DS is not a fan of bottles, although we keep trying, the real issue is that he is a snacker.  I've been BFing on demand since his birth and he has yet to set any real pattern or schedule when it comes to eating.  He is also kind of a "snacker."  He often nurses for 3-5 minutes on one side every hour or so throughout the day. 

How on earth do we know how much to put into his bottles?!  Although I have a decent freezer stash built up, I'm obviously not interested in wasting any by putting say 3 oz into a bottle and having him only take 1 oz.  Has anyone else dealt with this?  What should we do?  I'm considering just making a bunch of small bottles (like 1-2 oz) and H can just warm up more if he needs it.

Help!