Your symptoms sound very much like a combination of anxiety disorder and depression or dysthymia. I dealt with / deal with these things too. I'm 36 now and life is pretty interesting and good, but I remember being right where you are when I was in my early twenties. It's especially difficult for smart, introspective, creative people because you think that you should be able to "fix yourself". While it can be possible to pull yourself up out of a depressed state, it sounds like you are too far down to do that. You really should seek help from a psychiatrist who can determine if you would benefit from medication. The medication is hopefully a tool to give you the mental space to get up and stay up. I don't know what the access to mental health care is like where you are or if there is a big stigma with being diagnosed with a mental illness; I hope that's not the case.
One thing that I did not see you mention was exercise. It's so damn important. You must force yourself to be active, ideally early in the morning - I know from my experience and the experience of others that even a half hour of exercise can help with your mood for the rest of the day. For me it takes the "immediacy" of anxiety down a notch.
Aside from exercise, establish a daily routine and stick with it. Get up at the same time of day, eat at the same times, exercise, sleep, etc. - the consistency can also help with anxiety and becomes a framework into which you can fit all of the other "things" like learning and coding.
I wish you well. I'm sure that a lot of us wish you well - from all over the world. Every human is beautiful, precious, and worthy of being happy and not suffering.