You can do it!
Is anything more difficult than learning to knit after
you've become proficient at crochet? Which method are you using? I have yet to manage knitting not using Continental. I learned knitting on plastic needles and luckily the stitches didn't slide too easily. They're cheap...but mostly they were in the kit I found marked down and finally decided to go for it. I agree, use needles that don't encourage the stitches to slide off and just keep at it. You'll get the hang of it. It's worth the effort and time, IMO, because knitting is just better than crochet for some things. I'm currently on my 4th sweater, I didn't really start knitting till last summer.
Check out the videos here and any you might find elsewhere (youtube has lots), sometimes no matter how well done and how clear a particular demo is, I need to see another from someone else, you might be the same.
As for stretched out stitches, right now don't worry about them. In time and as you get the hang of 2 needles, 8 fingers, 2 thumbs, 2 ends of yarn....2 many moving parts
... you'll see fewer and fewer stretched stitiches.
One last thing: If you get really frustrated, put it aside for a while and pick it up later. Knitting should be enjoyable.