Storing breastmilk and then what?

I have been pumping 50oz-55oz of breastmilk a day and my LO only eats 34oz-36oz a day. So I'm basically storing quite a lot of breastmilk. I have a standard sized fridge and the ice box section is half full with the breastmilk. Of course we need space for our regular home groceries. My husband and I are considering buying a separate deep freezer box. The only concern is, what do we do with it after we use up all the breastmilk we stored? Is it worth buying one? I really want to stop pumping as soon as I stored enough for my LO's 6 months of age.