You are able to overextend your spine in the squat. This will potentially prove injurious in the future. You should maintain normal spinal extension during the squat and focus on keeping the torso immobile. Getting your back in a more normal position should help with hip drive. You are keeping your shins almost perpendicular to the floor. Let your knees come forward more early in the squat. This will allow the quads to work harder. You get plenty deep and your knees aren't wandering around, so things are pretty solid. Stop arching your back so hard and let your knees farther forward. See if that helps.
How tall are you, what do you weigh, and how much weight have you put on since starting the program? You don't appear chronically underfed, but putting on some muscular more bodyweight may be what is needed.