So, some backstory, I guess.

Probably a couple weeks ago, I was passing 3.6 star songs on osu!, or so. Pretty good for me since I started playing around 2-3 months ago. Then I went to stay with my grandparents for a couple weeks, and found myself rapidly improving, passing over 4 star insanes and managing to hold my own for a little while in 5-star songs. It was pretty awesome, it finally felt like I was improving. Anyways, when I took my desktop back to my house and set everything up, I noticed that I was having trouble doing things that were simple beforehand. After a little while, I realized that my desk was actually too high in comparison to my chair's height, and this made moving the mouse around awkward. (I'm guessing this is why I got stuck at 3.6 star songs for a while.) It might not sound bad, but I am playing SO much worse than I know I can, and it's frustrating because I know the reason, yet not how to deal with it. Osu! is kinda like an escape for me, it's something I genuinely enjoy and like challenging myself with, but it's really stressful to feel like I can't play it because my desk is 2 inches too tall.

I thought about possible solutions; using a cushion to raise me up a little bit (unreliable and not effective, would gain maybe an inch at best), replacing my chair (also not possible; my chair's seat is 18 inches from the ground and apparently, they make absolutely NO 20-21 inch chairs. Seriously, across 4 stores, it was either 18/19 inches, or a barstool, which was 24-25 inches.), or replacing my entire desk (which would seriously be the biggest pain in the ass, and probably be the most expensive too. I'd REALLY rather not do this.)

Now that my bitching session is over, can anyone offer possible solutions? (For those wondering, my chair's seat is 18 inches from the ground, and the top of my desk is 29 inches off the ground. The distance between them is 11 inches. Apparently that's too much.) I'm pretty stressed about this, and I feel like there won't be an easy solution, but if anyone can think of one, that would be fantastic.

Yea my old desk was ~29" - 31" inches. Playing keyboard on top of the desk was really uncomfortable no matter what height the chair was at.
I bought a new keyboard height desk that sits at 26". It was under $100. They are hard to find though as 30" is the standard writing desk height.

Your best solution is to bring the keyboard and mouse to a lower level not getting a higher chair.
If you are average height your desk should be 26" inches for keyboard height.
If buying a new desk is not an option I guess you could try and find a keyboard tray that is large enough for your mouse too.

You could get your hands on some wooden boards and place them on your floor, then the chair on top of it. That'd be the cheapest solution but it got its downfalls...

Man I remember the last time I had a panic attack too, I was throwing up black stuff that the internet told me was dried blood and my body went into shock and I almost passed out at 3 in the morning man yeah i totally get how you feel man

yeah reminds me of the time i had a little sparkle in my vision that gradually grew bigger and the internet told me i was going blind and i woke up fine

Do what I do! Lay down in bed and play osu!