I've been there anon and I'm much older than you, don't give up. I even quit drawing for years. Study hard but also post work for critique, open a thread every now and then if you get ignored in the drawthreads, and ask specific questions on things that don't work for you. You're going to take a lot of shit by crabs but someone will give you actual advice.
If you are too depressed to draw then put the drawing aside and try to see a therapist, get a job and a social life, work on making your life qualitatively better, you will be able to draw better as well.
Art is a quite lonely thing to do, but you can try to connect with artists' communities and share your work. You should have an easier time doing that since you like anime instead of niche things.
And if you're not improving it's because you might be studying from anime, you need to learn construction, at least the basics of realism will help you a lot even when you draw manga.