Guess My Sort of Favorite book

I Will Give you clues and try and guess my sort of favorite book


1: It Is a Series
2: I Used to read it at the library but not anymore cause I finished the whole Series
3: The mean girl's name in the series is Mackenzie
4: The nice girl always gets a Happy Ending
5: The Main Character (Nice girl) Name is Nikki
6: She has a Annoying sister called Brianna
7: One of the books are Called Pop Star
8: The Cover of Pop Star is Orange