So here's the thing, your forehand is almost a continental flipped over, and unless you use a longer swing than you do (think Jack Sock) you're really gonna struggle on the power. I'd say that you don't really use your legs in the swing either. Rotation will have to be there if your grip is that extreme, but the timing will always be hard. You also don't prep early enough.
The good stuff,
You hit with heavy enough top spin to aim high over the net and give yourself good margin, you also can afford to take the ball at your shoulder or higher with that extreme of a grip.
This is what I think;
You should work on turning your grip, wether it's a semi, and learn to use your legs and brush, while you hit through the ball, or stick with this and really work on engaging your quads and lengthening that swing. Realize your potential to hit flat drives is much lower than a less extreme grip, and if you're okay with that then just keep working.
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