I'm saying something different: does it remove enough DDT from the mothers body to affect womb development of subsequent children?

I see your logic and it makes sense. My point was more that if we posit DDT in breast milk caused autism, we'd expect to see a difference in rates of breast vs bottle fed kids, which we don't. So I'm skeptical of it being a big player, but I'll admit I haven't looked into this area deeply.

Not sure if this is what you meant, but breast-feeding a child wouldn't increase the autism risk for that child -- the damage would have been done by then.

You would need to research the occurrence of autism among children of breast-fed mothers vs formula-fed (i.e. a cross-generational study). I'm not sure if that has been studied as extensively as you assume.

Breastmilk is the evolved complete nutrition for babies. Various milk formulas are developed towards that goal. You cant compare these with the assumption they do perform the same - it would be like using Soylent 2.0 as the control for adult dietary research.