Out of curiosity I looked up the world record for the largest chicken egg, it was a whopping 201 grams!
Although yours was not this large it was HUGE!!!!
I am by no means an expert, but that is awfully white for a pullet, and from my understanding pullets have a black "wash" on their legs. Again, I'm not an expert, I am pretty new to this chicken thing.
My Marans are much darker than that, and their barring is not as uniform.
This one is 6 wks, maybe the comparison will help. Are you sure you don't have a little Barred rock roo? But, please bear in mind I have no idea what I am talking about
She may be an f2 silkie cross, if both parents were silkie crosses, she may have inherited the silkie feather gene from both of them. I do not know about silkie genetics, just a guess...