Yes, I think this is exactly it. Perhaps if I had started with ballistic stretching at the beginning it would have gone badly, but because I had been stretching for so many months I had certainly developed a sense of my limits.
I can kinda see why a physio would warn people away from ballistic in general -- there's probably a liability issue, when people have no body-awareness and go too far as you say, and hurt themselves. And it's certainly not to be recommended for stretching the back!
For spinal mobility I've been trying a few things, though it's going pretty slowly. What kind of things did your physio recommend?
i had several thing advised by him, but by now there replaced by stuff i learned from chinese teacher, works better.
there's one for spinal mobility, but it's to complicated to teach in words, or even by a little film. Took me much looking and nudging before I got it. These things are generally best learned from someone who can directly show you and correct where you're not getting it