I work with doctors that review occupational injury cases and treatment. Physical therapy has its benefits. Evidenced based guidelines such as ODG, state that about 8-10 sessions over 4-8 weeks is about all that is beneficial. A good PT, will educate you in exercises and postural changes. There are some exercises that in theory can relieve the disc pressure on the spinal cord, but it will likely not be more than temporary.
Have you had an MRI that confirms a herniated disc is impinging on the nerve root? Even so, pathology on MRI is rarely an indicator of the back pain generator. The spine is very tricky. Studies have confirmed that the majority of the working population have bulging and herniated discs with no symptoms at all. Then there are those with excruciating and debilitating back pain, but have no findings on imaging studies whatsoever. I found this out for myself last year when I hurt my back stretching of all things. I had terrible back and right leg pain to the point I could hardly walk for weeks. I finally went to an orthopedist, had a x-rays and and MRI, which were virtually normal. The main thing found was that I had a congenitally fused sacrum and L5 vertebrae, which means my back is not flexible like everyone else's. No more deep yoga stretches for me. Since then, my back pain resolved and my chiropractor's postural recommendations and changes to how I position myself when sleeping have made all the difference.
Therefore, choose your physician wisely. Many doctors are quick to do the old school routine of 4-6 weeks of PT, a series of three epidural steroid injections, and when those fail they finally suggest surgery such as discectomy or foraminotomy. When these surgical procedures fail to relieve the pain, then the physician often suggests spinal fusion. This is no longer considered medically reasonable according to evidenced based criteria.
If you are only having pain in your back, then continue your search for conservative treatment that does not include injections or surgery. However, if you are having radicular symptoms such as leg weakness, leg pain and/or leg paralysis, then you probably have a more serious issue that needs to be addressed.
I have reviewed thousands of medical files dealing with failed back surgeries, and I personally know family members and friends who have suffered greatly after their spine surgeries. All of them agree that they were better off before surgery. Surgery should be your last option once the pain keeps your from being able to perform normal daily activities and work.
As far as injections, I know of many people that have found relief afterwards, but it is normally short lived. Some have relief for only 4-6 weeks, and some for several months. It's an option, but does have risks since the injection is deep into the spine.