I have been playing for about 2.5 years now and I would like to increase my 1st serve speed. I hit a flat 1st serve with continental grip. I have tried jumping but it really doesn't feel natural for me, and my serve usually doesn't even go faster, and I look like a fool. I do a pretty standard motion, rock forward, then back, high toss in front of me, knee bend, then rising up and hitting the ball with a pretty standard flat serve swing. However, when I increase racket speed, I hit wild serves all over the place, rarely in. My 1st serve is extremely consistent, but slow and attackable, and I don't know how to increase racket speed, because even though I practice this a lot, it is still inconsistent. help me serve faster please.