Good or bad supply??

Hi! My baby was 3 weeks early and has some trouble latching so I’m exclusively pumping at the moment. I use the Medela Calma nipple so she won’t get used to an easy flow and never return to the breast because I plan on actually nursing again soon. She is exactly one week old today and eats about 2oz every 3 hours. I use a hand pump every 4 hours and get 2.5oz from each breast within 10 minutes but after that no milk will come out. Is that a good supply or too low? And if I use an electric pump will I be able to pump longer?