how much did your son weight when he was born?
instead about worrying about how much he weighs and how much he is eating, worry more about his general health. is he healthy? is he happy? does he have a healthy color in his skin and eyes? is he starting to be active? those are things that are MUCH more important than exactly eating a certain amount or his weight.
pumping is hard. i did it during my 19 months of breastfeeding and i always had trouble, although i KNOW that i had plenty of milk. when my son was around 13 months old i had such a strong let down my son was leaking it out his nose while feeding! it sounds uncomfortable, but he didnt care. LOL. he would giggle about it :P
anyway, one thing that i know worked for me to pump more was if i heard my son crying. so if there is a way for you to record your son crying on an mp3 player or cell phone or something, and listen to it while pumping, that might help you. especially if you record him crying or fussing when he is really hungry. it sounds mean, but it helps. also a picture of him while pumping.
when it comes to supply, demand determinds supply. so nurse often, even at night, and dont give him a bottle if you are present. once you pump, breastmilk can be at room temperature for up to 24 hrs, so you can have dad do one night bottle feeding to help you out a bit. chances are you will wake anyway, so it might just be easier for you to nurse. pumps will not stimulate breastmilk production as much as your baby nursing, so like i said, if you are present, you should never give a bottle. it may seem for a while like you are feeding on empty, but its important for your son to be 'nursing' during that time in order to stimulate an increase in supply! :D its a good thing. its going to seem for a while like all you do is sit and nurse nothing to him, but its worth it and required for more milk production. in no time, you will be back to a more 'normal' schedule. growth spurts are always like this - they want to, like be attached all day!
one thing you can do to help is get a moby wrap, they are extremely comfortable, and baby can nurse while being in one (though its sometimes easier said than done....)
so, 24 hrs room temp, i dont remember fridge time, but i think its up to 3 days. if you dont use the milk at room temp in 24 hrs, freeze it and then you have started a storage of milk for times when hes perhaps more hungry than normal or something like that. its always nice to have that stuff in storage.
another great use for milk in storage is putting it on major cuts and scrapes, it heals MUCH faster, and pretty much eliminates or reduces scarring from big scrapes. my son got a good scrape on the side of his head, and putting milk and a bandaid on it once or twice a day he healed up in 3 days with no scabbing. it was pretty nice.
what else what else..
www.askdrsears.com should have some GREAT info for you.
another place that is important to look is the la leche league. they can help you with SO MANY THINGS its unbelieveable. www.llli.org - contact a local or nearby group - the closest to me was an hour away... and go to their meetings. its usually only once a month. the wealth of information there is amazing. :D
good luck! :D any more specific questions you can sure send me a note! :D