Nothing is gonna magically make you better and I'm not near any of these pro players, but I'll give you some more mental and general advice that, when I actively remind myself to follow, work well for me.
REMINDER: I am ascendant 3. Not a very high rank. Keep that in mind if you end up reading these tips.
1) Notice how in most of these clips they are barely counter-strafing when they're actually in a face to face with the enemy. You can strafe while holding to not fall asleep, but as soon as you engage immediately stop moving and focus on your aim (Not a good idea when you're in the open where multiple people can shoot you at once). Also I wouldn't recommend crouching at mid to far range, but you do you because I also crouch instinctively and am guilty of it.
2) If you are consistently able to have crosshair at head level, when holding angles you should try to avoid moving your crosshair as much as you can and wait for the enemy to be in your crosshair. It sounds dumb, but this will prevent over/under flicking as much, allow easier adjusting to the next enemy if they peek, reduce the amount of bullets you use, leading to having better control and it will be another aspect of helping you play more confident. With that...
3) Confidence helps.. a ton! Don't be afraid of dying! It doesn't mean re-peek everything like a lunatic. Have concise/fast decision-making. Whatever you're doing commit to it. When you're holding, if you're worried someone might lurk up on you/you might get shot from a different angle, you can occasionally check it, but do not spaz out between the two. This will destroy your focus and that's how you end up whiffing everything, including util.
4) Most importantly, if you got the rank you are by yourself, or with a duo of similar skill, really no one has any right to be angry at you for playing bad or not winning gun-fights. Listen to your team if they point out your mistakes in a reasonable manner. Do not take what they say to heart and mute if they're unbearable. What matters is, if you want to get better, YOU need to be aware of your performance and what you're doing right or wrong which, sounds like you are :)