Breastfeeding and Pumping Help

Rachel
I exclusively breastfed and I hope I can keep up. My child is 10 weeks old. I breastfed her about every 2-3 hours. We give her one bottle before bed. I try to pump for 10-15 minutes after breastfeeding and store it.  If she is awake and wants to be held I miss my opportunity to pump. 
My nipples are still sore and sensitive. She has a good latch. I've tried nipple cream and my own breastmilk. Should my nipples still be sore after 10 weeks?
How many ounces should a 10 week take?  What about a 12 week old? Do they start taking more ounces less often? 
How do I keep up when I return to work? How often and how long do I pump during the day?