Most discs that prolapse go back on their own. Some don't. If you have been having physio and this has gone on for months then it's unlikely it will.
I understand about the not sitting/not standing for long periods. Neither is comfortable. I can't sit on my sofa anymore it's too soft. I have found that a hard dining chair with a cushion on the seat is best for me.
I'm not working, thank goodness. It would be impossible as some days I can't stand upright. I do try to walk as much as possible, driving is ok for a short distance but I have lost confidence as I don't feel I have enough strength in my legs, so I rarely drive. Being a passenger in a car is also not good. Sometimes if I am in position too long I can't move and I have sat and cried as it has taken me 10 minutes to get out of the car.
I would be wary of chiropractors. The treatment can be too harsh and whoever you are going to needs to have access to your scan to see what the problem is, and where it is.
You should not be carrying anything about, certainly not heavy books. Can you ask for help with that?
My physio says you have to tickle the nerve rather than stretch it. I know it feels as if you want to stretch it out. Your movements/excercises should only be to the point of pain, not pushing through it. Nerves like to be slid through their sheath gently, not twanged or stretched, this helps with the inflammation. So be careful with your Pilates, only small movements and only to the point whereit starts to hurt.
Another good thing to do is put a cushion or pillow, there is also a foam block you can get, under your bottom so the edge is just where the disc is, and lay flat on your back on the floor. This opens up your back and takes the pressure off. I do this when I have walked too far. I'm sorry i can't give more advice as that is all I have found to help me.
You do know that with choose and book you should be given choices of where you want to be treated, so if you were not happy with your first physio ask your doctor for another referral. My physio didnt do a lot of manipulation, just gentle exercises, hot and cold pads, tens machine- which really helped, and acupuncture- not sure about that.