Back Muscle Defect

I have a back muscle defect and I’m trying to find out what it is called. I know that I was born with it. The muscle is located in my mid/lower back and pertrudes outwards only on my left side and not my right side. It doesn’t have pain to it..just sometimes uncomfortable when sitting for awhile and with me getting older, i’m 19 right now, it seems to becoming a bigger issue. I know it isn’t scoliosis I think maybe the muscle is the wrong shape?If you have any idea of what this is or have any questions that could help then please contact me. Thanks.