Yes it is correct you need 2 playthroughs. I would also like to point out that I believe you may have some of the characters confused. For example in chapter 2 the wt refers to the player character as Kate when it is actually lauren you are playing as. There is a pretty decent reference on youtube if you are confused about the story of slender or who the characters are here
https://www.youtube.com/watch?v=Ibe6ORC_ykAOther than that well done thumbs up and please do repost this wt on the xbox one as im pretty sure it is exactly the same