A lot of places will send free chicks with your next order if you paid for pullets and they didn't meet their guarantee. You might want to look into that once you find out for sure what you have.
I'm no help in the Silkie department. Just got my first Silkies yesterday!
I am not so sure its a roo Give it alittle more time. Sometimes the girls don't have the greatest top knot when they are young. I have two pullets now that we thought were roos. They both turned out to be girls. Their crests are finally getting big any puffy.
With those wattles at 8 weeks, I'm 98% sure that's a roo. If the wattles continue to grow, it's a rooster. Pullets don't get wattles until a month or so before they start to lay...I have had pullets get tiny little pink wattles as chicks, but they are never bright red and they don't grow any larger and redder until closer to laying.
I just posted, probably in the wrong place, under raising chicks giving the reasons why I think my Polish streight run are one roo and one pullet. You guys are making me doubt my conclusion. My Polish are almost 10 weeks now and there was not much difference at 8 weeks. My hen grew waddles the same time as my roo, but hers were lighter in color. They are redder now and she is not ready to lay yet (really not ready to lay if she is a he!).
I will try to get some good photos, maybe tomorrow, to post that show the difference and see if you guys agree. Tail feathers are a big part of it. His are longer and he holds them higher.
As for the Silkie, what a cute fluff ball that is!