Well, everyone is different, but when I was making what you are, I was increasing 1-2 ounces per week...of course I did not take the bcp's, just did dom and herbs. At the moment I seem to have hit a plateau, but I have had a busy and somewhat stressful couple of weeks... both pumping and meds have been erratic at best..
Good luck with your pumping! You will probably find that once your baby comes, your supply will increase more quickly. But you can still have a great nursing experience even if the Lactaid is necessary. Do you have a Lactaid to supplement with once your baby comes? I used one the whole time I nursed Joshua, and it is a great gadget. Our nursing experience was very satisfying, despite me only developing about a half-supply of milk for him.