One misconception that I often encounter is that all Buddhists have a single mold that needs to be followed. From this misconception, it's easy to form misleading questions in the form of "Should Buddhists do X?"
I disagree with this line of thought. The Buddha recognised that while all individuals seek to liberate themselves from suffering, the immediate objective that they strive for can vary.
Just as you cannot teach the concept of impermanence to a devotee who has starving parents and children at home, you cannot expect one teaching to fit the needs of all beings. This is also why you can never measure someone else with your own standards. Buddhism is an introspective practice.
As such, asking "Why do I want to have children?" instead of "Should a Buddhist have children?" would encourage more answers of practical value. If I want to have children because it will bring me and my family joy, then yes, it's something I can consider.
Or, if I am someone who likes to inspect further I might ask, "How long will this joy last? What happens if things don't go as planned (illness, accident, conflict, etc.)?" And even then, I might decide that the joy outweighs the risk and go ahead with it. And nobody can fault me. I have carried out my due diligence in weighing the pros and cons, and decided that this is the best path I can take given my present circumstance. And that's okay too.
What I wanted to say is this: being a Buddhist isn't about subscribing to a set of "should-dos" and "should-not-dos". It's about recognising where your present circumstance; where you spiritually want to be in the immediate and long-term; and deciding on the best way to achieve that.
Being a Buddhist means that you are accountable for your own actions. There's no arguing with some deity when you get into trouble even when you followed instructions to a tee.
Q: Should you have children?
A: Are you sure you should let others tell you what you should do? ;-)