I would just like to clarify that a doujinshi is not limited to amateur manga publications. Doujinshis are "self-published", yes, but they are not limited to amateur manga publications. Professionals can produce their own doujinshis as well for the following reasons:
1. FANART OF PREEXISTING INTELLECTUAL PROPERTIES
2. ECCHI MATERIAL
3. One-shots
4. LEGAL REASONS/MATTERS
well most of the doujinshis we see are a combination of 1, 2, and 3, so i dont have to expound on them lmao.
As for the 4th one, an example for this is https://imgur.com/a/GhFXxGr. this is a doujinshi created by the original author herself. However, yaoi is basically considered illegal in chxna OR any works that depict a sexual relationship between men. Therefore, the author can only self-publish a doujinshi in order to "get away" with it.
what is the difference between doujinshi and yaoi?????