That’s exactly the answer given to you above - the line is murky and grey, there is no clear point that everyone agrees is the right point.
In such a circumstance, the right answer is open to interpretation, and the right solution for a society is to accept that the best person to make that decision is the person involved.
If you want my answer, it’s when brain cells develop enough to start looking like a functioning brain (somewhere around 16-20 weeks). Before that it’s just a brain dead mass of cells regardless of how it looks.
Clearly you have a different moment, and that’s fine, but you don’t get to ignore that the issue is open to interpretation. Otoh, I admit that both sides are guilty of trying to railroad a “simple” interpretation as the only right answer, it’s always tempting to force a simple answer and declare the problem solved, it’s harder to let people decide for themselves what the right answer is, but that’s the right thing to do when we as a society cannot reach a consensus, and we certainly don’t seem to have a consensus on this one.
We’ve already lucked into a solution to the population boom, the numbers will level off around 10 billion. Given how intractable population control is, we’re very lucky we’ve found this without some dystopian shitshow.
In the developed world we are approaching the opposite problem, we’re currently dependant on immigration to maintain our societies, but as the rest of the world stops growing we’ll have more trouble getting that immigration and won’t have the local young population to care for our elderly.
Given that we should be trying to figure out how to encourage a sustainable population whilst we still have time to do so. If we can choose between 1.9->2.2 children per couple as needed then we’ll be in a healthy position to slowly reduce the population to a comfortable level.
Right now our natural population decline in the developed world is too fast, probably because our society has made being a parent quite an individual burden. Of course, totally moving the costs to a societal model would be a disaster, but presumably there’s a middle ground where people are comfortable keeping the society going at a healthy rate.