frozen breastmilk

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I have about 90 oz of breastmilk In my deep freezer, and I pump while I'm at work every day too. I've been pumping exactly what my baby eats while I'm at work. Should I be freezing what I pump today and use the oldest frozen stuff for my baby to eat tomorrow? Or should I keep my frozen stuff as an emergency backup and give my baby the fresh pumped milk?