We had two sets of twins and a singleton afterward. When the last one was born we had 3 who were 3 years and under... it was a lot. Ours was a conscious decision (not the twin bit) but to have them close together because their is definitely sacrifice that comes from having even one young baby and we were keen to have a 'see through to the end' that stage in their life with the lost sleep, endless nappies and juggling childcare, mat and pat leave etc.
Having multiples is was wonderful for us, but it is a 'public affair'. I really heard what you were saying in terms of other peoples comments and reactions. I know when it felt like we weren't coping to have someone say 'how do you cope' and wanting to say back 'not always very well' was hard.
In parenting, other peoples expectations are a burden that seems so unnecessary and seems to add to the real stress and burden of keeping them happy and healthy - as well as ourselves.
We went to twins classes arranged by TAMBA (as it then was) and the most useful thing we were told was to ignore everyone else's advice, comments and expectations and don't stand on ceremony when it comes to accepting help. When friends and family stopped by (especially in those early days) and said casually 'can I help'... don't hand them a baby, but get them to make the tea, put some washing on, tidy the front room!
Everyones circumstances are different and my wife had a history of depression and so we were hot on making sure she had the help and support she needed knowing she would be vulnerable at those times - and still is.
Be are blessed to be together and a team, but not everyone has that luxury, but as a dad, another twin dad said before our first, 'remember that mums have A baby but parents have twins'. I've never yet met a parent who thought one wasn't a struggle, let alone more.