If you’re having this many difficulties you should probably just do something that’s more natural to you, there’s plenty of other things to do with friends that aren’t as fast-paced and demanding as competitive tf2 lol
I don’t get any of the things you describe but playing the game especially at a high level late before bed makes it difficult for me to sleep, lately I’ve had a lot more enjoyment casually playing pubs or other (non-fps) games with friends at earlier hours in the evening. On the topic of overstimulation it’s often hard to realize when you are actually overstimulated, I was having a lot of stress from work but it turned out that cutting tf2 out made it improve dramatically