The entire contrail has the consistent dark and light pattern. Due to sunlight and self shading. The image from another event from December 31st has a cloud shading parts of its plume. But that is understandable, since it appears to be a plane. Perhaps you are confusing the two.
So, yes, that proves the object is traveling from West to East ~ and we know that because the cirrus clouds in the distance are between the contrail and the Sun over the horizon.
We have low lying clouds all the time here off the coast. Sometimes they even come down to sea level. Called marine layer and fog. Have even seen low lying clouds moving one direction, and higher clouds above them moving in the opposite direction. Welcome to the mountainous coastline of the largest ocean in the world.
I really was hoping our flight would go somewhere else quick!