I'm right-handed but started with Conti, so it's hard to say how long it will take. (I did crochet for years, so holding the yarn in my left hand was natural. And mind you, my left hand is pretty useless otherwise
.) I do know that I have the same problem knitting English and have to wrap the yarn in a really odd way to maintain any tension at all.
You might try varying how you wrap the yarn in your left hand. For instance, I had to stop wrapping the yarn around my pinky because that wrap made the tension far too tight. I now just pinch it between my pinky and ring finger, and loop it over my forefinger as per the video. How you hold the yarn doesn't really matter as long as it works for you; I guess the trick is finding which way works. Just play with it, and keep us posted on your progress!