Yes, when loose, it is easy for little twists and turns to creep in. I like to set my grip and bring my arm up to stroking position rather than using a dead hang like TH. This puts the cue in a stable position relative to your body. Then build the base around that arm/body relationship. There are obv little tricks to how you lock it in but you can figure those out on your own (or buy the info off an instructor near you).i tried the "holding the cue at the balance point" thing that thorsten does, and it doesnt really seem to work reliably, at least for me. Sometimes the cue goes to the left slightly, but it really just seems to stay facing straight ahead. I am now seeking some instruction from a good player. I have been connected to a really good straight pool player who is willing to help me. I just need help with a pre shot routine, grip, stance, and stroke.
So you can't be unconvinced it is your PSR/stroke holding you back eh? Maybe share the vid you took or take one with a mask on if identity on the internet is the issue. You would have to be in a really weak league to be a top3 player and have a poor stroke is all I'm saying. A teacher that works with what you've got and polishes it is likely going to work out better than one that does a total overhaul. To use a golf analogy, Jim Flick was a great teacher who prided himself on all his students having different swings because he taught them how to figure out how they want to swing. Knudson, on the other hand, was a great player himself but his approach to teaching was that if you didn't swing exactly like he did, you were doing it all wrong. If you get a Knudson type teacher, pay the one session and move on would be my advice.