I have four DC, (in 6 years) found myself in same situation and was also sterilized during the delivery.
I feel that people transfer their personal feelings onto me. Where I come from, four children is very upper class. The country where we live has a declining population and so I get congratulated a lot.
People who have challenging children or don't enjoy being a parent as much as they expected make negative comments. Those who wanted to have more but couldn't make wistful comments, and fellow parents of four make 'keep going' comments.
Don't let any of it bother me, the comments reveal more about that person than me. I absolutely adore being a mother of four. I was lucky enough to be able to stay at home for 7 years and now, as a Montessori elementary teacher, I now have three of them in my class. (The eldest has SN so goes to a specialist school).
We are all incredibly close and enjoy each other's company. They don't get to go on expensive camps, designer clothes or super luxurious holidays but we eat together, camp a lot, they have their own interests and swimming lessons. So I don't feel that they miss out in any way, in terms of affection or attention.
The only downside is I cannot keep up with the housework and really wish I had help. Or a lot less 'stuff'. (Our families are all in the UK). And I do feel like a taxi driver a lot, but the eldest two are starting to use public transport now.
And, I really really feel that I have earnt that glass bottle of wine at the end of the week.