Opinions please ....on breast milk storage.

Tiffany
So my daughter is 6mo. What I have been doing is pumping and putting some in the fridge for the next day (during work week) and then freezing the extra. Well now I have 2,600oz frozen. It's about 4mo old in deep freezer. I'm wondering should I be using my old frozen milk first and freezing my fresh pumped milk. Or should I keep giving her the fresh milk while I freeze my extra? I've never made it this far into breastfeeding so I'm at a loss of what to do.
Opinions are greatly appreciated!