As far as other people saying that children won't fill that void in your life - they could be wrong. I felt similar to what you describe, albeit much younger than the average new parent, and having a child did fill that need. That said, it brought up a new feeling of regret of having a child too young.
If you don't have children, it's not the end of the world. A child is fun, and I have had many giggles with mine, but I also have missed out on a lot of opportunity for pursuing and exploring passions that could also fill that hole. Given the added stress of and time consumed with children, I don't think I will have another. My husband and I have collectively agreed about the things that are important to us in life, and they are infinitely harder with a child.
All that to say, you know what choice is right for yourself and you still have time to make that choice.