Where did you heard this?

In the epilogue it was said that Harry and Ginny are merried and they have 3 kids: Albus,Lily and James,that Ron and Hermione are merried and they have 2 kids: Rose and Hugo,and that Draco has son named Scorpious.It's also mentioned that Neville is working in Hogwarts as Herbology teacher and that Tonks's and Lupin's son Tedd is a boyfriend to Victoire,Bill's and Fleur's daughter.But were was said what happend to Luna,other Weasleys,where do Harry,Hermione,Ron and Ginny work,and what are the middle names Lily Jr. and James Jr.I mean,I read a book at least 10 times and I haven't seen these stuff there.But when I was online I saw that Percey has merried Audrey and they have daughters Molly and Lucy,that George merried Angelina and they have kids named Fred and Roxanne,that Bill and Fleur have 2 kids more named Dominique and Louis and so forth.I also read that Hermione is working at Ministry of magic,that Ginny became a Quidich player,that Neville merried Hannah Abott,that Lily's middle name is Luna and Jame's is Sirius...So I was wondering did you heard about what happend to the other characters?Is it just a fanfiction that became popular or did J.K Rowling realy wrote it on her website or in some short book maybe?I'm just asking this cause I'm huge HP fan since I was 4 years old and this is the only thing I don't understand about it.