Gin, even though or maybe because I have four kids, I think I get what you are saying here. If your life is what you want it to be and you are content, that's just fine. Whatever society, your co-workers or family thinks...in the end it's you that will birth and raise the children (hopefully with your partner's assistance of course). Only you can decide and be okay with that decision.
At 25 you also have years upon years of fertility left if you ever decide you do want a child after all. These days women have choices and the ability to bear children safely much later in life than even one generation before us so no need to rush any decision. If in the end you decide to not have children, there's no reason to justify that to anyone..it's a personal decision after all.
Quite honestly there's far too many folks in this world that had kids that shouldn't have or had them for all the wrong reasons. At least you are making a conscious well thought out decision and no one can or should critize you for that.
I had my first child at 26, my fourth at almost 40. There were folks that wondered why I "waited so long to have my first" and then wondered why I had one "so late in life"...geesh...people are rude to be so nosey about what is really none of their dang business LOL