Hey-o! I read a bit and I'd love to give you a little critique as requested ^^ Gotta say, I'm really glad you're looking to improve your writing! Being open to honest feedback and not taking offense to it is a huge step, and one I had trouble accepting when I first started writing XD Good on you! Anyway, on to my review!
I noticed right away that you've got pretty good chops for interesting writing. What you have is compelling enough to keep a person reading, and it's got a decent, unique voice. I'll get to the parts you specifically requested critique on in a bit, but first, a few technical aspects to go over.
Dialogue Tags are the "he snapped" and "she gasped" after a direct character quote. Your novel is in first-person, past tense, which creates quite a few "I said"'s. If you're going to include a dialogue tag spoken in a neutural tone, make sure to end your quote with a comma instead of a full stop. For example:
"Stop that," I said.
If you have a full stop at the end of dialogue, followed by a tag, it can really break up the flow and make the text more difficult to easily read. Another thing I saw is you have a lot of dialogue tags. A good rule of thumb is, if it's obvious who is speaking, leave the tag out. So our above sentence becomes simply
"Stop that."
It's also a bit more powerful! "Said" is an invisible word, so most of us tend to read over it without much fuss, but every now and then your characters will need a different tone of voice. If you want to emphasize the way a character delivers their dialogue, then it's acceptable to add a more colorful word than "said". Still, if you can do without the tag, remove it!
Here's another technical thing that will help with readability: If you have a large paragraph that goes over more than one subject, split it up. In the paragraph where we see Chris's description, Chris says something, then our main boy dumps into description as the narrator, then Chris says something else. You can split that paragraph into three pieces to keep your reader's eyes scanning the page. I'll place the paragraph below for reference, changed with the basic structural edits I would suggest if I was being paid to edit lol:
"That's my fault," Chris said, yawning.
He had about an inch of hair, from what I could tell, though his eyebrows were MIA. Dark circles stained under his eyes. He'd always been sick, but it never felt right to ask.
"You got suspended? Didn't you just transfer to our school?"
That'll help a lot with flow! Paragraphs that are too short in clumps are obviously no bueno, and you have a decent balance and understanding of general structure already, so you're ahead on that one.
Now! For what you asked for lol I'll focus on description in general, rather than specifically character description (because I firmly believe they should be structured the same way). I'll use the above description of Chris for example. It's a very decent description already. I especially like how mentioning the dark circles under his eyes and him being sick often tie in together. For the less-observant reader, that tells us his health is causing sleeping issues, which is GOOD DAMN BUILDUP, LEMME TELL YOU
ahem
This kind of description is rich and detailed, but also static; the story stops for a moment so we can get the details. This is totally fine, but if done too often, can take the reader out of the text and remind them they're reading. The goal for all authors is to produce a product that consumers can lose themselves in. (I do static description myself all the time, and I'm still working on making it flow better. This is a more advanced tip that a lot of very experienced writers haven't mastered, so feel free to set it aside and continue doing the already-wonderful descriptions you're doing!)
A good way to get around stopping the story is to describe your location/person/item as the story continues, never stopping the action. I'll provide a before and after example of my own writing for context, so you can get an idea of what I mean.
Before
The man that gets out is slender, with brown skin, long, lean arms, a wide, toothy grin, and cleanly combed hair. It’s dyed the color of autumn leaves, and hangs around his chin. It’s early for winter wear, but the driver loops a multi-colored knit scarf around his neck as he shuts the door, covering all of his skin.
After
A man exits the car--though he's slender enough to fit through the window--with a wide, toothy grin tugging his cheeks as he smiles at Art. Even though it's too early for winter wear, the man loops a multi-colored knit scarf around his neck as he shuts the door, covering every inch of his brown skin. The breeze catches his hair, dyed the color of autumn leaves, and by the time he reaches Art, the ends have settled by his chin.
In the first example, we get a rich description, but the story stops for the narrator to tell it. In the second, we get a description that happens while the narrator notices it. It's the difference the narrator seeing aspects because of action, as opposed to stopping to look for a while.
OF NOTE, this kind of stuff I only ever notice and edit after my first draft. It's totally fine to write basically whatever comes to you, and to edit later. Not a single writer I've met in my life can do this on the fist try haha. I wrote an entire 80k word book and then spent like, two months doing nothing but editing it. Editing is where the magic happens!
WOW I DIDN'T MEAN TO WRITE THIS MUCH I SWEAR LMAO
I'm really passionate about helping people develop their writing skills, and I want to reiterate how impressive it is that you already have a voice of your own in your text. Voice is something everyone talks about, and it can be developed, but some people already have it. And you, friend, already have it!
My final advice is to just pay attention to technical grammar/punctuation stuffs, but otherwise keep doing what you're doing! It's an impressive beginning and you've gained an eager subscriber. I hope this helps you further your goal of improving!
(Forgot to say this earlier: I really love the title, it's so foreboding and cool lol okay byeee)