Anyone exclusively pumping?

Lisa • Pregnant with our first baby boy 💙 due sept. 14, 2015. 👼
Hi ladies
Anyone exclusively pumping? 
I am having lots of trouble with my son and breastfeeding so I'm investigating exclusively pumping.  Here are my questions 
When do you pump? Every two hours? Three? 
How much do you pump in one sitting? Because I only pump between 1-1.5 ounces in one sitting which is not enough for my little guy for one feed. 
How long do you pump? I've been doing between 10-15 mins. 
Thanks