I feel pretty relaxed already playing much weaker, similar level and stronger, since I started playing matches and points more often, its just slightly weaker that im getting a bit tense because I expect to win but also know they are not that much worse so I can easily slip up and then might get even more tense when I make a few errors, I guess its a bit of an ego thing, since I expect from miself to beat them and if I don't and lose to someone whos not as good as me my ego is a bit hurt I guess.
I got through about post #40 here and I'll read the rest of them, but at this point my advice is to go find yourself a copy of
Mental Tennis by Vic Braden. This book is one of the all-time greats written by one of the all-time greats in the teaching/coaching realm and he was a bit of a player in his day, too. If you want to get your head together to become a more effective player going forward, I know of no better resource than this book. Bonus points for Braden's style of story telling - much fun and very easy to read. More bonus - it's super cheap in paperback!
Don't know whether we've broached the subject in the past, so apologies if I'm being repetitive, but I'm wondering if you've worked on the mental discipline of playing with a fundamental plan from point to point? If not, I think your time has come. Yes, I learned a bit about this (among other things) from reading Braden.
Instead of going out on the courts and assuming that you should beat some "slightly weaker opponent" nine times out of ten with your stronger game, planning your points will help you to focus on actually doing that. The idea is to focus on what you are specifically going to do in this moment to create an advantage and win a point. Instead of simply chasing down anything your opponent throws your way, you'll already know what to do to better control the action once the ball goes into play. The discipline is learning to do it over and over again.
If you can get used to this mental ritual, you can play sharper a lot more often and also become more immune to the setting and the match score. Whether you're up a set and a break, dead even in the middle of a third set, or down an early break right out of the gate, planning your points keeps you dialed in on what's the best thing to do right now. Learning to do this will absolutely unlock more of your potential to play a more competitive game.
Yes, there are some other helpful things you will learn along the way, but I'll bet you at least a nickel that planning your points is the biggest step forward that your game needs right now. Braden's book also digs into confronting our expectations of ourselves on the courts - this will be a biggie for you, too. You sound like you have a sense of "something" that you need to work through to build toward your next level, so I think that you're closer and more ready to take that step than you think. A little self-awareness will turbocharge your compete level big-time.