This is the first thing that came into my mind: http://www.mangago.me/read-manga/renai_shijou_shugi/
Thankyou! ♡
http://www.mangago.me/read-manga/crossroad/
http://www.mangago.me/read-manga/tenshi_ja_nai/
http://www.mangago.me/read-manga/kirai/
http://www.mangago.me/read-manga/guru_guru_pon_chan/
http://www.mangago.me/read-manga/gokinjo_monogatari/
http://www.mangago.me/read-manga/w_juliet/
http://www.mangago.me/read-manga/limited_lovers/ (not as long as you'd like but it's good)
I tried picking ones that I don't think are too popular..but IDK if some of these actually are :S
I already read most of the popular completed shoujo and im running out of mangas to read.. ╥﹏╥ Please recommend some completed shoujo! It would be better if its long or atleast it has 30 chapters because i enjoy long reads! Thanks (づ￣ ³￣)づ