Hello J.-
I think 3 oz. is a lot for you to be getting from the pump at one week. At one week, my daughter was still only taking 1 1/2 ounces of milk at a time, and I think I was probably only pumping 2 ounces at a time, about every 2 hours.
My daughter was in the NICU the whole time we were in the hospital, making it difficult for me to nurse her. I allowed the nurses to convince me that she wasn't getting enough milk at every feeding (how the *H* could they know that!) - and they ended up supplementing her with formula. When we got home, I stopped the formula completely and focused on nursing. Things were fine for the first couple of days, and then the slurping started. It was painful and frustrating, and with those baby blues, it was just awful. I was very committed to breastfeeding exclusively, so I called a lactation consultant to come over. She was fabulous - even though she wasn't able to help me resolve the issue completely, she provided some much needed support (that was harder for me to get from my family). I had started pumping in the hospital and had pumped in between nursing sessions. After about 8 weeks, I gave up on nursing and exclusively pumped. When I was exclusively pumping, I was able to get up to 15 ounces in my morning pumping. Even at that point, my girl was still only getting 5 ounces at the most in a bottle. I was able to stockpile loads of milk in my freezer...I even had to give some to family to store in their deep freezers. She was eating every three hours, so I didn't get the time break between feedings that formula would have provided, but I was okay with that.
Around 6 months, I decided to try nursing again, and voila! It was almost like magic. Our latching issues were gone. I now nurse exclusively, and only pump every now and then so hubby can feed her. I can't explain what happened - I'm fairly large breasted, so maybe her mouth got bigger and that helped. I don't know.
My point is keep trying! Your beautiful boy is only a week; it hasn't been long enough for the two of you to get the hang of it. Most breastfeeding experts say that it takes 6 weeks to get in the groove of it. Stay focused and good luck!