How long are you pumping? Do you feel "let down" b/c if you don't you may not be pumping long enough. Heat or massage helps with let down, so you may try a heating pad before pumping or massage your breast a little. Now, about the pump. You don't need to rent a hospital grade pump. You have the same pump I do. It comes with standard size cups or "horns", they may not be the right size for you. I believe they are 24's. I bought 28's and 30's. They allow for you to get more of the nipple/aerola section in for pumping. Believe it or not, it does help with getting more milk. You can buy these at Riverview Hospital and if they don't have them, they'll order them for you. Another thing you can try doing is taking an herbal supplement called Fenugreek. Take it with Blessed Thistle. If this doesn't make a difference in your milk supply within 72 hours then it's not going to work. I was on meds called Reglan to help with supply and man--does it work! So, if you need to contact your OB/physician and ask about Reglan, it doesn't harm the baby at all (they actually give it to babies). As far as how much she should be getting--at the least 2 oz. per pound. So at 7 lbs. she should be eating 14 oz. or more. Don't give up on breastfeeding even when you get frustrated--I totally know how it feels to not get anything from pumping. Another thing you can do... if you don't want to do meds or if you just can't get the supply you need, you can always mix formula and breastmilk. But the problem with mixing the two? What isn't used after a feeding within an hour will have to be thrown out. So I would suggest keeping them separate even if you alternate feeding her breastmilk and formula. If you have other questions, you can always go by Riverview Hospital during their breastfeeding support group. It's Thursdays from 10:30-12 and they have a certified lactation consultant. She is WONDERFUL!!! Her name is Rosemary and she would be glad to speak with you --free of charge!
Oh, and make sure you are getting plenty of water and eating well!
P.S. The more you keep your breasts empty, the more they will fill up!