Breast feeding and want to pump for supply

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I’m having a hard time getting time to pump in between feedings. My 4 wk old is so fussy aNd it takes forever for her to fall asleep and nap. Hence she has to be held or in my lap. Carriers don’t work. Therefore when is best time to pump bc I feel that by the time I get her down she’s only napping 30-45 mins then up again and then almost time for another feeding session. Yesterday when she had a longer nap I did get to pump and get 4 oz each side. However when I went to feed her she was distressed and crying on the boob so worried I emptied and not getting enough....

If I go back to work in 3 months how much oz should I pump now per day for daycare 10 hrs a day???