What are your skates cut at? If you watch your feet as you are getting ready to make a save, often they are sliding outwards and backwards.from under you. So as you get deeper in your crouch, they want to be wider apart. Get your feet wider, I know you don't think you can, but you can. They are trying to do it on their own. When you do that, you'll be able to engage your edges better. You'll stop slipping so much, and you'll find that your movements are a lot more powerful as a result. Get your skates cut to 1/2 or 100/50 FBV at the very least (I skate on 100/75), you need to make them as sharp as possible. Shuffling will be more difficult, but you can learn how to do it. You can't learn how to make your edges sharper if you are slipping. Also, watch as you drop to make a save. Often, you pull your feet backwards so they are touching behind you. That's leaving the 5 hole very exposed, and severely limits your ability to move. Also, it leaves your knees more exposed to being hit with pucks, and puts more strain on them. I'd say you are more likely to hurt your knees that way then by dropping with your knees in. If you get your feet wider, you'll be able to engage your edges and drop by bringing your knees in. I also just noticed that when you drop, you are dropping your butt and sitting down. That's why your feet go back. You're bringing your weight backwards over your legs, which puts strain on your knees and forces your feet backwards. Focus on keeping your butt and hips straight up. You want to drop forward, keeping your weight over your knees. You'll find there's a lot less strain and pulling that way. Your angles look good, and your reactions and battles are good too. Get your feet wider to get those edges involved and you'll really see an improvement.