Are you right or left handed? It wouldn’t have mattered in old China as everyone was forced to hold a writing brush with their right hand. Left-handed was not allowed. I suppose the same would probably have been true for holding a seal carving knife during imperial times. Due to the shape of Chinese characters and the way they are written it may be particularly difficult to form them properly using the left hand (I haven’t tried), but in carving seals it really doesn’t matter which hand you use to hold the blade. The cutting motion, and the result, is the same no matter which direction you start from. So if you are left-handed don’t be discouraged. Carve seals. Nobody will know the difference.