Having a microdiscectomy surgery at the young age of 15 years indicates that you have a genetic predisposition for degenerative disc disease. This is a problem that you will need to deal with by learning how to reduce the load on your spine with ergonomics and core strengthening. If you are still having significant problems with your back- you need to get an opinion from a spine surgeon. It may be that you have an unstable disc that can be stabilized through surgery. You may have a recurrent disc herniation that also can be rectified. You may have a pars fracture which is common at your age and can be fixed. Do not despair but get more information about your back.