It is unlikely to be endometriosis. The shape of the abdomen is defined by your muscles and fat. If you would like to post a picture, it would help.
I assume you mean your left, the appendix scar is on the right. There can be endometriosis in a c section scar which is fairly common. This could make the scar and area around it more tight. It looks like it is the c section scar that is distorting your abdomen.