My kid sister cannot have children. So, she's a great "other mom" (not yet stepmom) to her boyfriend's son.
My youngest sister cannot have any more children, as she had her son just before she turned 40, so she's a great mom to her only child.
I was told I couldn't have any more children after my first one, but I had 3. Go figure!
One of my best friends simply doesn't want children, and neither does her husband. Some people just don't and there is absolutely nothing wrong or selfish about that.
Frankly, this is a personal choice and no one has a right to tell you if your choice is right or not.