Re: Horrible butt wink...help
I vote to stop worrying about it.
You will always "butt wink" if you squat deep enough. Olympic Weightlifters will drop way below parallel. I am no expert, but I have a feeling they have a "terrible butt wink".
Your squat will fix itself. Historically people have been lifting things a lot heavier than you without much care for the shape of their spine.