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I don't think it's a weird shape at all...it's perfect for one person on a budget.
I do think the large table is too big. If you get rid of it, you would have room for a sofa.
An arrangement I like is bed and nightstand (like you have it...for me, I would put huge casters on it as I hate making a bed against the wall, but I do get that it's the best use of space)...so left to right on your diagram....bed (small shelf for water/book/light), sofa.. a couple "c" tables (you don't have room for a coffee table). For someplace to eat and work, I like a table that folds up to the wall...like this: https://www.amazon.com/CHANG-XU-DONG-Convertible-Multi-Function/dp/B07RS12DMK
They come at all price points and for 2 or 4 people and you can even diy one if you're handy.
I would have a chair that can be used for study, for guest seating, and for eating...so I would probably get 2 comfy-ish chairs, and if you opt for the 4 person seating, I would get 2 folding chairs and hang them on the wall https://thefurnishingartist.wordpress.com/tag/decorating/
This should leave you room for clothing storage.
Ideally, get a loft bed. This will be your best buy and (bonus) lots of people want to get rid of them, so they're all over Craigslist.
In a space like this, it's important to use walls for storage--think vertically.
Get yourself some wall decals for fun.
Most importantly, have a master plan and start out right...don't half ass it and use "it's good enough" as an excuse. Because honestly, you can get depressed if your environment isn't what you want.
Congrats on school and your new place! Be excited!