Your upper body is static. There is no upper body rotation and, therefore, no kinetic chain - the chain of events beginning with rotation of the right hip toward the target, which pulls the torso, which pulls the shoulders, which pulls the arm and racquet, which leads to the rapid supination pronation of the arm into contact aka "the flip." Rather, your legs and upper body are motionless and you are merely hinging from the shoulder. I will point out that it is difficult to fully execute the modern forehand, with the long finish and upper body rotation, against most walls because the courts aren't deep enough. A full swing will result in the ball bouncing behind you, and you don't have time to recover from the long finish of a modern forehand. Try to find a wall with a court as deep as a tennis court, including the 21 foot backcourt between the baseline and the fence.
This is a basic guideline: In your "set-up" position, at the back of your backswing, you should be set up in a wide, open stance (about 45 degrees to the target line), with your chest facing 3 O'Clock (from above), your right hand pointing to 5 O'Clock, and the top of the racquet pointing to the side fence, initiate your forward swing by rotating your right hip forward and allow the kinetic chain (described above), to activate the rapid supination/pronation of your arm. Your arm and grip should be loose, relaxed and mostly passive throughout the swing and follow through. At the finish, your chest will have turned nearly 180 degrees to 9 O'Clock, your elbow will be pointing to the target, and your racquet head will be down near your left hip.
