Look at high speed videos of ATP & WTA forehands.
1) look at the line between the two shoulders. Roughly that line turns back 90 degrees and then forward 90 degrees. The
shoulder turn is used much more than yours. And the
shoulder joint is not used as much or early as yours.
Separation is also very important. Please see my posts on separation.
Search forum:
forehand separation Chas
2) look at ATP ball viewing habits. It really is a zoo with Thiem closing his eyes, Mendelev flicking his head like lightening, Federer locked on well before and after impact and Djokovic doing various things. A question came up in another thread about whether the player was looking at impact through the back of the racket strings or not. ?
The shoulder turn is possibly the largest source of 'power' for forehands. It brings twisting the spine and the abdominal muscles into the ground strokes. If you have any issues with twisting be sure you are safe to twist your spine and abdomen.
3) Look at the tilt on the racket face for impact for top spin drives.
It tilts closed 5-10 d.. Tilts are shown later in this article. Some old bad advise for the racket face is 'hold face perpendicular to the court surface'. But that is not correct for top spin drives. What is your thought?
https://tennisspeedresearch.blogspot.com/2013/02/a-roadmap-to-hall-of-fame-forehand-part.html
Hitting against a wall & fence may not be giving you a reproducible feed to try new things. Also, the ball looks low. If you can get access to a ball machine or hitting partner, that would be better.
Choose straight arm or bent elbow forehand. Choose grip: Eastern Forehand for straight arm or semi western for bent elbow. Select model forehand ATP & WTA players that match your arm & grip. Observe the angles of elbow and forearm to racket shaft at impact.
Compare your forehand to ATP forehand one above the other and single frame. To single frame on Vimeo, stop,
hold down the SHIFT KEY and use the ARROW KEYS. To single frame on Youtube, stop, and
use the period & comma keys. Always select the Youtube video using the
alt key + left mouse click, otherwise the video starts playing. Go to impacts and single frame back and forth, comparing the most similar racket positions. For best accuracy use very similar camera angles.
Select a model WTA or ATP forehand Youtube or Vimeo and post it right above or below your video and copy the above directions. Use the same camera angle to record your forehand. Be careful to protect your camera from ball hits.
Djokovic has a bent elbow & Semi-Western Grip forehand.
post your video from the same camera angle.
List all differences that you observe. Many of them would probably be flaws.