you can do core exercises until you blue in the face but your therapy needs to address functional things like sitting. Your sitting posture needs to be assessed so that you can learn the optimal posture for your back. the chances are you may never be able to sit for 10 hours a day at the computer but who can? your back is designed to moved therefore you must allow yourself regular breaks when at work where you change position. I wouldn't be jumping into surgery lightly either as it doesn't always help.
developing a fear of movement is very common so your physio should be giving you graded exercise to prevent potential abnormal movement patterns.
consider whether your back is shifted (do you lean a certain way to avoid pain). this can be adaptive- your bodies was of trying to protect the structure or maladaptive- that youve done it for a while and you body forgets wherw it should be in space.
maybe you should get someone on here to recommend a therapist. I would deinately be suspicious of a therapist who hooks you up to machines for therapy and doesn't look at your movement etc.
good luck