Hey mate, so sorry for your current phase.

Well, I don't want to sound like a motivational speaker but you see that feeling of never knowing eough, it's there. I do experience it. But that shouldn't stop you from trying that which you want.
I never felt I'm good enough
on the literary world, connecting with international publishing houses, writing book reviews and other bookish things related. I still went ahead to give it a try and despite that feeling, I'm still greatful I did tried it out.

And also, on not finishing what you started, I feel setting a realistic goal can help. Like, I don't know much about coding but you can set it like within a specific month I would finish this and then, you try to see if you can carry a specific task.
It can be, today I'm going to learn fronting, tomorrow it can be to input a certain task and like that.. (sorry, I'm just giving instances like I said don't know related terms on coding).