doujinshi freak out (please read I need help)

Okay so for those of you who dont know what doujinshi is its basically manga that fans have made of a particular manga that they enjoy. From my experience there are a lot of characters put together in them. Now I'm having a little bit of a panic over this (A big one) because I have been reading these on a website called Myreadingmanga.info for ages now. But its only been recently that my anxiety has kicked into overdrive and now I am worried about getting into trouble by the police or something because the doujinshi I have read has been published on the site not by the original owner and its then illegal to read it or something. There is even a small part of my mind that's like "what if the characters in the manga are underage and I dont know it because there is almost no way to tell in manga." So I'm having a freak out right now. If any of you can give me advise on here that would be great and really help me calm down.

Somewhere in the back of my mind I know that its okay and if it wasnt then I would have gotten in trouble a long time ago but I cant help but be scared.

Also no nasty comments please because this is a serious issue in my mind. I know to some of you it may seem like the most ridiculous thing in the world but I cant help but be worried about this sort of thing