I'm not sure what products they have in Israel, but here you can buy freezer bags specially designed for breastmilk. You pump, put in bags, label date and amount, let cool in fridge then store in freezer. In a chest freezer they can last up to 6 months, less in a fridge/freezer. Then to reheat, you can put them in the fridge during the day or in warm water (don't microwave). If you can't buy the freezer bags there, you could probably order some online...
HTH!