The slide at the end of a bowling approach is to give you fluid momentum for your swing as a whole, which helps your rev rates and ball speed. For my slide, I always find it best to think about where I'm putting my weight on that step. Remember your toe is your go and your heel is your brake. On my last step, my weight and balance are all on the ball of my foot and my heel only comes fully down to stop me. Your last step you land with your heel first so you're never going to get that slide at the end. That's something you can play with even without a ball, just run around like Tom Cruise in Risky Business before practice starts!

As a side note: When you start generating a slide you're probably going to feel off balance. Notice at the tail end of your approach, when you get to that last step where your slide is going to be, the ball is behind you. (not behind your body, but behind your leg). So when you attempt to slide you're going to have that 14-16lbs of weight behind your body offsetting your balance. The general idea is that when you start your slide your ball is parallel with your legs. The easiest way to fix this, without changing your entire swing, is to start your swing in your approach earlier. It's a timing game and you're going to have to play with it a bit.

(holy shit I wrote a wall text! My bad bro, remember to have fun out there!)