Book with female main character it might have something to do with factions but I don't know if that's what they are called in the book.

I read a book 6 years ago and I LOVED IT. I can't even remember where I got the book from. Maybe audible or Google books. I also went back and listened to the audio book on YouTube but it's been deleted (I have a Playlist with all the audiobooks I've listened to.) All I can remember is the main character was a girl about to turn 18 I think and she went to her friends house because they were leaving to be sent to different classes. She goes and gets placed to be a medic I believe had a hard time making friends but eventually she makes some and a guy comes along. They fall in love. They have some sort of magic or something like that she discovers her mom married someone from the other class and was very high up in the class there was something about her playing chess with a mentor, she finds out the mentor is evil and they end up fighting to get the class system taken down.

 I think there was something about ravens, or angles or night wings. Maybe black blood?