There are various ways to freeze your milk, some of these are more costly than others. Here is a ranking of different ways to freeze your milk from the costliest method to the least costly
1. Medela freezer bags
2. Lansinoh bags
3. Ice cub trays and then transfer to Ziploc bags
When you want to defrost your milk best is to take it out of the freezer and defrost in the fridge. It generally takes about 12 to 24 hours to defrost. The defrosted milk should be used within 24 hours. You can then warm it in a bottle warmer.
Remember milk expands when freezing so be sure to leave some space in the freezer bag.
If you are in a hurry you can defrost milk by holding the bags under hold water. However some bags might leak so best is if you fill up hot water in a bowl and put the bags in another bag or Ziploc and then insert in the warm water. That way if they leak you haven’t lost any milk. Remember that once you have given the bottle to the little one, leftover milk needs to be discarded. It should also be used within an hour so treat it like formula.
At the beginning when my son was small and I wasn’t sure how much he would drink, I filled the bottle 100 ml and then refilled for another 100 or 50 when he finished it. That way I minimized the amount I had to throw away.