I remember back 4 or 5 years ago I always think my art was so bad much to the point that I hid it from the world. In my opinion, self-doubt arise when you compare your art with others. Before, my confidence was at an all time low because I see many artist who are younger than me and yet are leagues better and because of that I always thought will I ever get better in this. Despite that, I can't imagine doing other jobs than drawing so I just keep it on and try improving my craft as much as possible and I was able to slowly gain the confidence I need to show my art to the world. Of course I still think there's a lot of stuffs I should improve on my art but unlike before, I'm not comparing my art with others anymore.