I've been writing fanfiction since long before I knew there was a name for it. I began posting at maybe age 15? Or maybe 14. I was reading since 12.
I started with simple stories then moved on to adult fanfiction.
I have well over 100 stories total, at this point, because many have been deleted (due to the new format rules on some of the sites) and to my dismay, all of the adult stories I'd posted on one particular site were deleted because I'd written then before I was 18.