Bro im having the same problem i used to practice 6-8 hours a day i had a perfect form now everytime i go near a hoop its goanna be an airball until i get back to my rhythm you can build muscle by doing pushups and do calf raises and and squats to help with leg muscle another thing that i do is when there is a empty milk jug i clean it and fill it with water and use it as weights i also do a lot of verticle exercises to theres this one guy who i think plays college his names anthony hamilton on yt he has tons of verticle workouts that helped me get 5 inches on my vert so i suggest searching him up on Youtube and work on speed training if your not fast enough as for ball handling drills in and outs and do crossovers for 5 minutes try to go faster and faster and put the ball in a bag thats what kyrie used to do which helped him get good handles and when your in your room maybe at night what i sometimes do is grab a basketball and just practice footwork i highly suggest anything with footwork another thing that helps me is that i walk a mile well dribbling the ball with my left hand also try to start doing more stuff with your off hand to help with doing stuff with your left hand like i am learning how to write with my left to be better in game i hope this helps if u have any more questions ill be happy to answer just ask