Everyone is going to have slight differences between one side and the other, because we have naturally adapted to our own habits and patterns of daily life, or because we are simply born with a different balance. There isn’t anything wrong, this is totally a normal way to start out in yoga.
By what you say, I can’t visualize exactly what the problem you are having is, so I cannot say if you are doing anything incorrectly. If you can find a teacher nearby to watch you practice, they can distinguish if you need modifications to prepare for this asana, or ways that you can strengthen or stretch the side that is more difficult for you, so that you become more balanced altogether.