Claudia,
First of all it sounds like you are doing great. Remember that a baby is much better than a pump.
A full supply for a newborn is not that much because they don't drink much for the first few days. My DD drank less than 1-2 oz 8 times a day in those first weeks. After a couple of weeks the needs increase. kellymom.com is a great bfing website and they say that a bfed baby needs about 24 oz a day on average. So if you are feeding 8 times a day (the minimum you should feed a bfing newborn), they will need about 3 oz per feed. If you are feeding more often (12 times a day or so) then you would need less - maybe 2 oz per feed. I weighed my daughter before and after feeds and found she was taking a little less than 24 oz in a day, but she was a small baby to begin with. I think my bio son took more on average than that, but he was a big baby.
You can save it in the fridge until you get enough to freeze. I would start by freezing it in 2 oz increments. The lansinoh freezer bags are great and lay them flat when freezing, they are much easier to store.
Good luck,
Jennifer