You have buttocks and leg pain along with lower back pain. You have two levels of significance, L1-2 and L5-S1. Your symptoms of back and leg pain occur with sitting and are relieved with standing.
Most likely, the L1-2 level is not causing you symptoms. First, there is no evidence of any nerve compression here. The second is you don’t indicate any upper low back pain.
The L5-S1 level is most likely causing most of your symptoms. Herniated discs that compress the local nerve root (in this case S1) will cause buttocks and leg pain with sitting that is relieved by standing and walking. Lower back pain is caused by the annular tear.
A protruding disc with an annular tear is the definition of a herniated disc.
If you have no motor weakness (which would be noted as difficulty walking on your toes), then with three months of pain, if you were my patient, epidural steroid injections and therapy would be the next step in the treatment algorithm.
Donald Corenman, MD, DC is a highly-regarded spine surgeon, considered an expert in the area of neck and back pain. Trained as both a Medical Doctor and Doctor of Chiropractic, Dr. Corenman earned academic appointments as Clinical Assistant Professor and Assistant Professor of Orthopaedic Surgery at the University of Colorado Health Sciences Center, and his research on spine surgery and rehabilitation has resulted in the publication of multiple peer-reviewed articles and two books.