If there was no loss of hieght in the disk, shown on x-ray by having a good space between the bodies of the vertebrae, then that makes it less likely to be a disk injury.
This procedure, although I'm still not sure what it entails, sounds like a disk injury procedure, which in my opinion should not be carried out without definite confirmation of injury to the disk, that only a scan would confirm.
If I were you I would return to the practitioner that had helped you previously. 3 treatments isn't a lot all things considered and they should give you self help advice, that would probably include stretches.
It sounds like you have an 'extention' injury, which is why your lumbar curve is pronounced and this is probably due to the small facet joints at the rear of the spine being 'locked' together. It's these that she would have released for you, that gave relief, but you'll need to keep them moving with stretches & maybe work on posture etc, to re-educate how your low back moves.
That's a lot of if's & maybe's, but trust that you understand that I can only give it my best guess, but this sort of thing isn't uncommon.
Cheers - Andrew.