Chiropractors do not “straighten” the spinal column. The action of the manipulation (the adjustment) increases motion of a segment but there is no “the vertebra is in or out”.
Drop tables have advantages and disadvantages. The “drop” feature allows greater acceleration of the speed of manipulation and a quick “stop” of motion. This allows more force generation which I’m sure you can understand is both good and bad.
The good is that the chiropractor needs less force from his hands to generate a greater force of movement (good for the chiropractor as he or she needs to generate less force for the same motion as a DC without a drop table).
The bad is that force generation is amplified. If a chiropractor uses the same speed and force as a standard manipulation but uses this force on a drop table, amplification of force can cause injury to the structure manipulated. I have seen these injuries from a drop table so you have to be careful as to who you choose to manipulate you.
Your description of your alignment sounds like you have a scoliosis. This will cause a dropped shoulder and larger muscles on one side of the spine.
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.