I don't think the hackle feathers are a a good indicator or deciding factor on a 6 week old wyandotte. If you look up other laced wyandotte chicks, you'll see that they all look like they have pointy hackle feathers at this age.
6 week old pullet:
sorry - can't get the link to copy & paste here - the comb, wattles, stance, & hackle feathers looked like yours to me - it was definitely a female - the poster also had its adult pictures posted.