Hi there
A bf mod here. So I'm just going to focus on the feeding aspect if that's OK.
I'd firstly say that although a yield can be a useful exercise in some ways it doesn't always represent what you are actually giving baby when they feed. A baby is so much more efficient at extracting milk because of the wave-like motion from their lower jaw and a pump really struggles to come close. Some people are successful pumpers but some nursing mothers don't even get a proper 'letdown'. I know many successful nursing mothers who struggle to even get an oz and hear their own baby glugging milk down for 15 minutes during a feed. So don't use a yield as the only indication of supply. There are good tips about pumping here:
http://www.pumpingmoms.org .However don't forget that the hormone prolactin which governs milk supply is stimulated by this wave-like motion and that means the more feeding at the breast you can do the better.
Any amount of breastmilk your baby gets makes a difference - even if it is only a few oz - but I bet it's more than you think.
I said that a yield isn't the best indicator of supply. Your baby is infact your main guide. I'd ask when you feed her do you hear clear swallowing noises and see a pause in her chin movements when she takes a swallow? Also how does a feed end? Does she break off seeming satisfied? Are you the one to end a feed? Do you feel she is falling asleep before a feed has finished? If you weren't supplementing I'd also ask you about wet nappies.
If she's waking up hungry after 20 minutes and you feel supply is an issue then there are a few things to consider:
Make sure you are eating and drinking enough yourself.
Do consider talking to a helpline (there are numbers on the bf FAQ page). They can talk to you about baby's latch (just incase it needs fine tuning) and give you good advice about how to boost your supply.
Although pumping is helpful and it's great you are pumping at night. It would help your supply and your prolactin levels if you did a night feed (prolactin levels are highest at night which is one positive thing about people who have to night feed!). You just might want to think about making perhaps the 3am a breastfeed if you can. You could ask the helpline more about that.
When you supplement just make sure you are offering the breast first. You might also want to consider something called breast compression which can make feeds more efficient and increase the fat content of your milk. You can read more about that here:
http://www.kellymom.com/newman/15breast_compression.htmlThere is a mixed feeding thread on the bottle feeding board which you may find useful as you can talk to people about their experiences in combining formula and breastfeeding. Plenty of people mix feed successfully. If you want to try and return to more breastfeeding then I'm not sure what professional help you've had so far but it might be possible to increase your supply with some tips from a five minute conversation on a helpline. If you feel mixed feeding is the way forward then remember Tracy herself was very supportive of people who chose that route and you'll find plenty of people on these boards to help you.