Former baseball player too. When I first played slow pitch, I was jamming myself and hitting weak grounders on every swing.
The key for me was all about weight transfer. I think, for softball, that if you kept 100% of your weight on your back foot at all times, you wouldn't be far from wrong. That will do two things...first, it will force you to wait on the ball. I was jumping too early and shifting my weight forward, causing the groundouts. Two, keeping your weight back will natually cause a bit more uppercut in your swing, better matching the plane of the ball.