When storing breast milk in storage bags, do you prefer to freeze them as a flat bag or standing up? If flat bag, when defrosting, what method do you take on to ensure bag doesn't leak?

I freeze mine as a flat bag and after it is frozen i will pack them standing up. This is so as to maximise storage space. You can thaw it by taking it out from the freezer and put it in the fridge to thaw overnight. Alternately, You can run the bag upright under tap water to thaw it fast. Milk bags don't normally leak if they are closed securely. But there are times where there are spoilt bags. I haven't encounter bags that leak yet.