i also get these comments but we are TTC # 4 and i think the comments are worse ( not comparing though).
we have 3 boys and dh had a vas when last baby was 12 weeks old and i was sick. regretted it later but too late to go back.
anyway we get , why would you even want 4 kids, be happy with what you've got, why would you want to do this again ( as in have a baby)
be greatfull
and it goes on.
the thing is no matter what number you are trying for the desire for another child is the same, yes i do have children and i get to have a "mothers day" and i do know how blessed i am but the desire to finish our family is still just as strong as when i had my second or third.
i hope you get your BFP and 2nd child soon.
good luck