I had/have the same problem, when I decide to "play for real" and "take it seriously". I think I unconsciously tend to tense up and end up playing worse for my efforts, despite "playing for real". Likewise I've played more relaxed and ended up totally destroying my opponent out of no where and I'm not just talking about Chess, I'm talking about other things as well.
I hear you though, u feel like you've worked so hard, you MUSTTTTTTTTTTTTTT win right lol at least that's how you feel, ...but even if you have studied your arse off, you can still lose, especially if you come up against an opponent who's playing outside of the realm of things that you know well and have studied.
chess anxiety


Well, you can try this link (or not): https://www.chess.com/forum/view/general/i-cant-play-chess-due-to-anxiety
Of course, the obvious solution is to give up chess . . .

Chess won't make you anxious, it will only trigger your anxiety (big difference), that's why chess will make you less anxious elsewhere in life, not more. However, chess will make you paranoid. It's good to be paranoid when playing chess. Elsewhere in life, paranoia is good or bad depending on what you do and which situation you're in. Quite often, paranoia is bad elsewhere in life if it's too much of it.

eat dark chocolate and drink lots of coffee.
No and no, it will destabilize your feelings, you need proper food to stabilize your feelings. We're talking about anxiety here.

natural, u can start by practicing with cpu first, then after ur confident much higher, u can play with people around ur rating. don't afraid to lose, it doesn't kill u. nonetheless losing r much better than winning, u know where area u can strengthen after that game
hi! anxiety is fun! just take it as a challenge.. haha.. before, i usually play otb shivering, but as i play more and get used to it, it got lessened.. i think maybe the remedy is to just to face whatever it is..

The game has a calming effect on my mind
Sometimes that's why I play chess. Time control 5|5.
I stopped playing Bullet chess a few years ago, apart from a brief session again a month or so ago in which I dropped 100 rating points! That was mostly because I found it made me more stressed rather than being a relaxing, or even fun, game. I never exclusively played bullet though anyway. My staple on chess.com for years has been Daily chess and a 10 minute game each dinner (lunch) time at work, plus some Crazyhouse if it ends quickly. I don't find 10 minute chess adds to stress or anxiety in general, though occasionally I care enough about my rating to not want to play in case I lose points. It's rare though and only when I've been on a good run and reckon it is bound to end!
For me it's just a game though normally and I play it in my lunch break at work in order to take a clear break from working and its related stresses, even though chess is still brainwork it's fun.