The second flashback happens either before or after the liberation of the Ruins of Lordaeron (considering she says that she is already building a new kingdom and mentions the term Forsaken, it may be after the battle).
While Tales of the Hunt states that Sylvanas became ranger-general following Lireesa Windrunner's death in the Second War, Dark Mirror clearly shows that Sylvanas was already an established ranger-general before the Old Horde had reached Quel'Thalas in the war.
It could be speculated that Lireesa was actually killed during the interim between the First War and Second War.
The following texts were not published as short stories but rather published on the official Blizzard websites as blog posts split into several parts. However, they are included here for completeness' sake.