The Dragon Diaries is a paranormal young adult trilogy, following the adventures of Zoë’s coming of age as the new Wyvern of the Pyr. It’s a spin-off series from Dragonfire so details about the series can now be found on the Dragonfire Novels website. The books should be read in order.
In terms of timeline, Zoë’s coming of age takes place when she turns 16. She is the daughter of Erik and Eileen and the result of their firestorm in Kiss of Fate. This series is set in 2025, long after the end of the Dragonfire Novels, so you could read it after Firestorm Forever. The series was written, though, when I was writing Darkfire Kiss, so an option is to read this trilogy after Rafferty’s book.