Frost Feathers on the shortest day

Photographed on the back window of our car on Midwinter's day.
Did you feel anything special at 17:28 Swedish time (CET) 16:28 GMT? That's when we passed midwinter, or if you are in the southern hemisphere midsummer of  course. For us northerners tomorrow the day will be a little longer and the sun just a tad higher in the sky at noon.
But I'm puzzled! According to a reliable website our earliest sunset was 17 December, so the sun has already been setting a little later for 4 days, and latest sunrise will be on the 28 December, so we still have a week of darker and darker mornings.  Why is this?  I tried to find the answer but I didn't understand it!  Something to do with solar noon...
But the frost is beautiful and the days are getting longer - I'll be content with that, especially as we'll be in England from tomorrow night!