It sounds like you are doing great! I am guessing that you are adding in those 2-3 pumping sessions in between nursing sessions.
Some advice... based on my experiences. Take what you need and leave what you don't.
Overall, you'll want to make sure that baby is nursing every 2-3 hours (8 times a day). But that varies greatly. You can add in pumping sessions after your DD nurses; either right away or wait about an hour and then pump. Keep in mind that you won't be able to pump as much as baby is able to transfer via nursing.
As far as pumping goes, it is better to pump for a little bit longer. About 15 minutes per side. Do you have a good, double electric pump? You will want that when you go back to work. I wouldn't pump any more often than you already are. I've heard a few different theories on pumping in the beginning. You want to be careful about getting an oversupply which could lead to baby getting too much foremilk. So they often say not to worry about pumping in the early days.... to let baby regulate your supply to how much she needs. However, I wish I had pumped more to get a stock supply up.
3-4 ounces per pumping session is also pretty good. Especially if you are nursing full time on top of that. I find that my production varies greatly throughout the day. I can pump 6-10 oz in the early morning and 3-5 oz in the afternoon. I'm working full time and pumping every 3-4 hours at work depending on my schedule.
And one final tip when pumping. Your pump will stimulate a let-down and then your production will slow to almost nothing. You can usually get a second let-down by turning off the pump for 1-2 minutes and then starting again. My pump starts off at a high speed suction to stimulate the let down and then it slows down after 2 minutes. It has a "let down" button which starts up the high speed suction which I can press after my first let down to stimulate a second let down. I hope that makes sense.
I hope that helps... you're doing great!!
Amanda. Mommy to my sweet pea born 8/9/10. Breastfeeding and completely dairy and soy free due to allergies in Mom and Baby.