Axial lower back pain for 15 years, visual analog scale pain of 2 increasing to 5 with exercise is annoying and problematic but not disabling. It appears you have tried many treatments without success. The key to managing lower back pain is core strength and ergonomics (how to move, lift etc..) Core strength will stabilize the back to allow lumbar motion with less stress on the discs. Pilates treatment through a skilled physical therapist would be the next step.
You can try epidural injections as these can be effective for a period of time. Non-steroidal anti-inflammatories can also be effective. Testicular pain can occasionally originate by referral pain from the discs of L4-5 and L5-S1.
Dr. Corenman