Hey Tim, your backhand technique is definitely not terrible at all, I think it looks very good! Just make sure you are finishing forward with the bat and pointing the wrist out where you wan the ball to finish, which mostly you are doing well here anyway. You are brushing over the top of the ball well so keep that up too, similar to your forehand I would just say to keep the arm relaxed and the movement smooth.
Lastly try to not let the bat drop between each shot, so keep it high as you recover for the next shot, this will make it easier in a game to be in position quickly for the next shot. But don’t be to hard on yourself this looks good and it’s only small changes, overall your backhand is solid!
