Good for you mom for pumping for your preemie!!! Best decision I ever made for my 32 weeker. He had to have formula for about two weeks because I'd gotten the rubella vax. His little tummy was so messed up till he got back on my milk.
Pump every 3 hours just as if baby was nursing. Give yourself a 4 hour break at night to get a little more rest. You need enough rest to make good milk.
An ounce at 7 days old is right on track. Trust me, you *will* be able to build a supply by pumping. I was not an over-producer by any means and we had a huge supply of milk that we brought home from the hospital when he was ready to leave. You can build a supply for her by just pumping.
It was very interesting. Every time my son was ready for a slight bump up in the amount he was taking my body starting making more.
I pumped every 3 hours for 12 weeks straight until I was able to teach my preemie to nurse. He was in the hospital for 6 weeks and then we began to work on nursing once he got home and got into a rhythm.
Try pumping just past the 20 minute mark as well. Once my body learned how to work with the pump I would get another great let-down just at/after the 20 minute mark.
You can also gently massage your breasts while pumping. Once you get a supply going you will be able to feel the full parts and massaging them helps your body let-down.
Keep letting baby try to nurse at the hospital. That is the one thing I wish I had done differently! I think it would have made a huge difference.
If you don't have them get the Medela Steam Clean bags! They will save you a huge, huge amount of time with cleaning the parts. You won't need to boil them if you use the steam clean bags.
If you have any questions, please don't hesitate to message me! I went down this road and we went on to successfully and exclusively nurse for 16 months!
Congratulations mom!