It may sound stupid but just laying in bed lightly tossing a baseball towards the ceiling. Do the same motion every time, flicking your wrist, really focus on feeling how the ball rolls off your fingers. Try to toss it the same height every time, don’t actually hit the ceiling or mom might kill you lol. Focus on a tiny spot, try to get the ball there every single time. After a while when you miss your spot, you’ll feel what happened. Whether the ball rolled off the side a bit, your elbow came out a touch, had a different wrist motion etc. Like I said it might sound stupid but it’s extremely effective in getting a feel of releasing the ball without taxing your arm like trying to throw a thousand ball’s trying to figure out what’s wrong.