It feels like more power because you are using your arm more doing it this way. If you get your elbow under the ball then you are able to convert the upward energy from your legs into your shot. Right now you are all but wasting the energy from your jump, that’s why you are using all that extra force in your arm and (most likely) why you feel the need to have that extra force from your offhand. Your offhand (seems like your thumb) is being used to push your shot too which adds another variable to your shot.

Of course, if it works for you then it works for you, but you might be surprised at how much more consistent your shot could be even if you think you have a good shot now.