50mls is a champion effort I expressed double what I usually can from my boob for the first time last night which was the equivelent of 10ml an hour for that boob so, I'm very impressed with you.

Yes, you can add it all together if you want, just be sure that temperature's of what you are mixing together are the same. So, if it's room temp you can add newly expressed stuff straight into it, if the container has been in fridge or freezer, you need to cool down the newly expressed stuff in the fridge before adding it.

It's really up to you about the size of the containers and depending on how much she eats - but I would say freeze it in portions of the amount she takes at one feed. You can always defrost more than one batch at a time if you need more, but you don't want to waste any precious EBM if you defrost too much IYKWIM. Avent sell these portion cup things with a screw on lid - and also you can buy a direct teat attatcher if you want. I'm too unco to put liquid into soft bags and try and keep them open and not spill it etc, so I always used them.