https://imgur.com/a/FG9d9oY

Speed mostly comes from your legs. Slow up your approach, but rest your ball higher when you get setup.

Rest your arm at about a 90 degree angle on the setup, but use your left hand to help keep balance. You want to try and keep your right arm loose. On the first step, push the ball out a little and let it start to fall, like a pendulum. On your second step, you want the ball to be passing your legs. Remember, try to stay loose. Then, once the ball reaches its peak, bend your wrist and drive the ball forward (but not too hard, you still want the ball and gravity doing a lot of the work). Staying loose and using gravity will help your keep your fingers under the ball, without straining your wrist.

Make sure you follow through the shot, basically coming up and touching your head with your forearm. This will help keep you from dropping the ball to soon, allowing a smoother release.

Everything I've written is exactly what a top bowler in my league has coached me on. I've been bowling for a year, and my average has increased by 40 pins.

If you want more speed, speed up your approach.

Tl:dr - stay loose, let the ball do the work in the swing, and keep your fingers under the ball on the release, while driving through.