How much should I really be pumping?

Po
My baby (who is in 95th percentile for size) only eats like 10 oz while I'm at work during the day. I'm pumping like 20+ oz during that time in 3 sessions. What's going on?? I'm only at work 1 day a week. My boobs feel so full! Too much pumping?? All the other days I pump 5 oz each day.