Your analysis clearly shows that there is no way to predict how happy you will be with your decision. Which means only one thing: if you feel like having children, do, otherwise don't. No need to over-think it.

Assuming for a second that the analysis shows what you say it does it still doesn't mean that one thing. It would mean that the statistics about the effect of children on happiness aren't enough to base your decision on. It would mean that when making one of the most fundamentally life changing decisions you can make you will have to use different information than happiness trends. "Happiness" is far from the only metric with which to reason about a decision.

Unless your ability to reason is absolutely abysmal you probably are better off researching and "thinking" about important life choices. Especially when you have good reason to question whether your instincts are aligned with your own reflectively considered preferences on a subject.