I had to pump because my DD wouldn't latch. I had to pump for three months before we were able to get her to nurse at all. So yeah, I was pumping about 24-30 oz a day for her. If my supply dropped at all it was because I wasn't pumping often enough, so I just had to start pumping a lot more frequently.
I second the skin-to-skin contact, that really helped us. In the end though, we had to take the bottles completely away. She just wouldn't nurse if she knew there was a bottle to be had.