Himegoto - Juukyuusai no Seifuku
The short haired one is Yoshiki and long haired one is Mikako. These are first image is page 16 of chapter 30, second image is page 6 of chapter 31, and the last 2 are parts of pages 8 and 9 of chapter 31.
This isn't really a yuri manga though.
Just so people know, there is an official English release of Citrus here on Amazon. That is if you want to support your authors or want to see more media like this.