Why is there asymmetry in my stomach? the left side is higher than the right.

All bodies imperfect: Nobody has a perfectly symmetric body. Most of these minor imperfections we notice are just unique aspects of how we're built. A mass in the abdomen could make it asymmetric too. If it's large enough to see, it should be large enough for a healthcare provider to feel. If the abdomen is obese, an ultrasound could exclude any mass large enough to cause visible asymmetry.