Bestberries, Jillian has good suggestions. I strongly suggest you keeping the ebm cos every drop is gold!!
<font color="119911">You will need:</font>
1. pump, (spare batteries)
2. milk bags
3. ice bricks (buy extra from daiso, get those that fits the size of your cooler box)
4. cooler bag/ soft bag
5. cooler box (you'll know how many you'll need base on the volume you usually yield/day and for x number of days
6. labels
7. waterproof marker
8. Post-it pad
<font color="0000ff">Hotel</font>
Almost all hotels will accommodate your request to keeping your BM in the freezer then you collect when you check out. Ask the hotel to freeze your ice brick too. Else, you can always freeze the bricks in your minibar fridge, but dont trust those fridge to freeze your BM. And if you do put your bricks inside your room;s minibar fridge, stick a post-it on the door of your room so you'll remember to take them with you when you check out. (I have always left my ice brick/ cheese cakes/ yoghurts etc in hotel fridges, sayang)
<font color="0000ff">Aircraft</font>
1. Pumping--unfortunately, you can only pump at toilet if you want privacy although I have come across one mom who did her pump in the cabin in the mid of night. But her pump was extremely quiet, thot it was the Medela PIS (backpack). I only hear very soft humming.
2. After that, you can ask the crew to help you put in their fridge. If you happened to be on SQ, their B777-300ER, A380, A345 (I am sure their latest A330 would too) have freezer in the business and first class. Ask crew to help you put int the freezer, when you arrive, put the bag into your cooler box, the temperature should last till you get to your hotel, once you are there, ask the hotel concierge to keep the soft bag in the freezer. Do label your bag for ease of I/d-ing by crew & hotel staff.
3. The above mentioned aircrafts have electrical power outlet in the seat, the safest is the 2 pin plug (European), but no harm bringing along your travel adapter. I am not sure about A380 & A330, in the past, on the older aircrafts, you need to match the pins of your cord to the socket, and you'll need to twist before it can be fully inserted to the socket (safety measure).
Ask the crew to help if you encounter problem. SQ used to carry adapter/ splitter, but it's only limited quantity, so you may want to ask early. Now the splitter is for sharing, cos in the past it's 2 outlets: 3 seats. I was told in the newer aircraft this is no longer the case.
4. For return flight, I suggest you board early, and after you settle your bags, ask the crew to help you put the cooler box in the fridge or freezer to ensure the frozen ebm does not start to thaw. If they are unable to do it at the early part of the flight, your frozen ice brick and cooler box should last for sometimes. Crew may be able to accommodate by giving you some dry ice, or accommodate after the first meal service (7hrs flight usually has 2 meals service except an ex Japan).
I have never use the large fridge to go before, so I am not sure how good they are.
Bare in mind there are also restrictions on liquid, aerosols and gel that only permits 10x100ml bottles in a zip-lock bag.
If you are traveling in and out of Australia, the local customs officers are more sticky, so I suggest you declare if you have ebm entering. I hope they are more understanding to this.
Woah, so lor-so..
Do share your experience so we all can learn! And have a fruitful trip!