You need to engage your right shoulder more. It's not being used properly. All the other elements are there but I can see you're not activating the shoulder. When you make contact you can see your hitting structure dissolves. It falls apart because your not getting power/support from the shoulder. It's a big muscle. Use it. When you rotate use more shoulder to pull the racquet. Power through the shot with the shoulder.
Look at your form in the video above and then look at a pro. Compare the shoulder usage. Like djoko here. Look at his right shoulder. You can tell those muscles are being used. The shoulder provides power and leverage. Look how their hitting structure (racquet / arm / wrist / angles - relationship) stays intact after the hit.