Mine are also uneven. I was told that it was because of scoliosis. Maybe your muscles developed more on one side than the other because of an uneven posture. These are two possible reasons why they are uneven.
Stomach muscles
these muscles can move in your stomach in not a referable question pleese comment
you may be speaking of a Hurnia, an injury to the stomach muscles when the intestines come through the muscles of the stomach
do excerice
an adbomas
There are actually FOUR layers of muscle in the stomach.
Chyme
You run or walk with your legs. Your stomach is used to break down food. The two have different muscles to complete different tasks.
skeletal
Muscles, fat, and water.
It is most definitely involuntary. You do not have to make your stomach contract every time you eat something.
Stomach muscles, or abdominal muscles, are often referred to as a six-pack because of the way they appear. There are two muscles side-by-side at the top, two in the middle, and two on the bottom, which makes the stomach resemble an actual six-pack.