I've found that it sometimes completely flips. So if you think it's not getting any better, just keep going - tomorrow could be very different.
It was 15 years, and I started when I was 10 years old. I have a lot of damage to undo. Don't give up, we will all recover eventually.
Zero Had like a 54-day streak a few months ago, was flatlining the whole time. I very consciously relapsed thinking it would end the flatline. I regret that massively now.