why can't I pump?

LO will be 2 months on the 24th. When she was born she was in the NICU for 6 days and couldn't nurse. I pumped every 2 hours for those 6 days and my milk came in great. The first day she was allowed to nurse she latched on pretty much the first try and we've been doing awesome ever since. I haven't pumped at all since the day she started nursing. She's on a regular schedule with eating. I decided I should probably start pumping at least once a day for emergency bottles and such. She sleeps every night from 830- at least 130. During the day she eats every 2 hours. I figured somewhere between 1030-1130 at night would be a good time to try to pump since that would fit into her 2 hour schedule. I just tried for the first time and got less than a teaspoon of milk. I pumped for 10 minutes. I'm so confused. Is it because my body isn't used to feeding her st this time? Should I just pump after a feeding? Idk where to go from here. Help!!