It looks like you are set up with the bar behind midfoot and hips a little too high. Starting with the bar another 1/2 inch or so forward, with shins inclined to touch the bar, will help you set your back better and produce a better pull.
It sounds like a light squat day and the DL switch are warranted now. Start with 1x5 at 80% and just let it go up from there. Add the second set when your LP is over. I'd put the heavy DL day at one end of the week, and the light DL at the other - you'll quickly re-adapt to pulling after squatting. So your week will be
A: Squat, Press/Bench, Heavy DL
B. Light Squat, Press/Bench, Chins
C. Squat, Press/Bench, Light DL
With light and heavy DL days being interchangeable, i.e. if you want to put DL heavy on Day C and light on A, won't really make a difference - as long as it's the same every week.