As someone who rarely plays any OTB chess games, I recently decided to go to some USCF tournaments to get some OTB experience. On chess.com, my rating is around 1900-2000 (but was 1800 at the time of the tournaments), but was very dissapointed at my tournament results. I frequently lost to USCF 1200 players, made gross tactical blunders, and had huge strategic oversights. Almost all of my mistakes were obvious during analysis after the game, even without any help from Stockfish.
One good example is from an advanced french position where my opponent played Nb5, threatening Nd6+ (defended by Pe5 and forking my king on e8 and rook on c8). After around two minutes of thought, I decided to play Rc7??, straight up hanging my rook in one move. Fortunately, I managed to save the game with a well-timed simplification into an equal endgame, but that is besides the point. I also noticed that I kept making strange opening choices in blitz games, not playing any of my usual lines, as well as missing obvious refutations to dubious moves from both sides. Not to mention huge tactical oversights and overall lack of calculation ability.
I think the appearance of the board with 3d pieces and perspective is throwing me off, but I'm not really sure how to fix this. I don't usually have any opportunities to play over the board, since there aren't any major chess clubs near where I live, but I was wondering if there are any sorts of practices or books I can do by myself on a physical board, or some other advice from anyone with a similar experience.
And to be clear, playing against other people isn't really an easy option. I've already looked hard for any nearby chess clubs, and all the tournaments I've gone to are several hours away. It seems fair that I should do some practice before driving several hours just to lose miserably at a tournament.