Definitely large!!
Large better to have too much room than not enough
Large for sure!!
If go with a Medium Eastpak Tranverz. Or something that splits equally in two halves to make it easier to find things. However I wouldn’t make it babies case. I’d use it half for you/ your OH too because if it goes missing (ours did on our last trip) You’ll be cursing having put everything in one case. Also we bought 4 Tot bot wet / dry bags to organise clothes. Also great for using there for swimwear or dirty clothes etc…
Thanks! Went with a large to be safe
Just be wary of the weight limits with any large case. Our full medium was 20kg. X
Large!