You do flex your back a little, but it is not awful. Have you tried pulling in weightlifting shoes?
I wanna cry right now, I've rebuild my deadlift more times than I can remember, I can do five reps with a bent back up to 145kg but its just getting out of hand and now I've literally lost around 6-7 months of potential progress, heres a video any advice would be much appreciated:
https://drive.google.com/file/d/0B2F...DByVFJUOUpkRFk
You do flex your back a little, but it is not awful. Have you tried pulling in weightlifting shoes?
Don't put wedges underneath your feet. If you have weightlifting shoes, try wearing them.