You're amazing for continuing to try to bf. Do your best to take the pressure off of yourself (I know that's easy for me to say!) Stress can have a negative impact on milk production, so try to relax and be positive.
The SNS is a great option b/c it'll allow her to continue stimulating your body while she gets nutrition.
If you are pumping _after_ she nurses, that could partially explain the lack of colostrum and milk when you pump. We had minor issues when my LO was born and for the first few days I pumped after she nursed and was very worried that I never got anything out until my milk came in after 2.5 days. I would hope that by now you'd be getting some milk when you pump, but if she is latching on and sucking then she may be getting at least a little bit of nutrition.
I have seen someone else suggest that you and the baby get naked (well, keep a diaper on the baby! :) ) and crawl into bed for at least a full day. Only get out of bed to go to the bathroom. Other than that, have the baby up close to your body, skin to skin, and let her latch on and nurse as much as she wants. If you can do it for a couple of days, then go for it.
Drink as much water as you can stand. I'd aim for at least a gallon per day. If you have trouble drinking that much water, add a little flavouring to it - maybe a slice of lemon or lime. On days I let myself get a little dehydrated and need to drink a lot, fast, I tend to make a quart of Gatorade because I'll usually suck that down faster than a quart of water. I know it's high sodium but I figure it's better than being dehydrated! :)
Other moms have also suggested eating a lot of oatmeal.
Keep in mind that you are doing your best, and for whatever reason it might not work. Try not to beat yourself up, because as I said earlier stress can significantly decrease your milk supply. While formula can't provide quite everything that breast milk does, babies can thrive on formula and do very very well. If that ends up being the route you have to take, try to be at peace with it and enjoy your LO. Her love for you will not be lessened any.
Good luck to you - I hope some of the suggestions you get from the moms here help you out!