Did you ever get your answer? I have a silver leghorn. In December, she was just old enough to lay. I have all brown and green egg layers other than this newest batch. I suddenly started to see a white egg nearly every day for about 1 month. Then... no more whites. My 5 newest egg layers are 2 brown layers and 2 EEs one lays green and one lays blue. I have a total of 9 hens and have been convinced my silver leghorn stopped laying since the only missing color is white and I did get a month of WHITE. So, best guess, she is on laying break. But, I have on occasion found a blue egg and a egg so close to white, I think it is white until I take it in the house out of sunlight and am certain it is a whitish sky-blue. My Silver Leghorn looks exactly like yours. Nothing special on her head. Not likely any question she is a true silver leghorn. And, again, I was actually getting white eggs for 1 month before they stopped appearing. So, guess only time will tell for sure. But, was wondering how things panned out on your end.
Thanks