Oh wow, people say some dumb insensitive things! You really want to scream sometimes, don't you!
You aren't less of a mother because, for now, you only have one, and i think it's awesome that you love your time with her and you miss her. That's so cool.
One small silver lining is that now, you and me, and all the rest of us here are slowly educating 'these insenitive people' and I can only hope that we are making just one more person stop and think before they make comments like that.