Breaking the norm - not wanting children

When asked if I want to have children one day and I say "no" people usually reacts with surprise, especially when they find out my age. Of course they are to polite to question it straight out but I can see what they really are thinking, that I´m breaking the norm, that it´s weird and that I one day will regret this decision. To me on the other hand it´s more weird to have a child because it´s something I "should" do/have in my life. I know though that I´m not alone in thinking like this, due to non of my friends having children of their own yet.
Anyways, considering that I at times even think my dog takes up to much of my time, (sshh don´t tell her), I know having a child at this time would be disastrous. For now I´m therefor quite content being a cool aunt to my sister child.