I have 2 SLW pullets that have different feathering, but look very similar to yours and I have seen pics of SLW that sometimes I guess can vary quite a bit and not all look the same and still be female, the males look very different and as someone already posted will present the male pattern around 6 wks. I'm not sure what causes the difference with the female variations but there are people on here that could probably tell you about alleles and which chromes go to what and attach to what and came from who, etc......