Some of my personal favorites that are completed:
http://www.mangago.zone/read-manga/rumspringa_no_joukei/ (6 chaps and one of my all time favs)
http://www.mangago.zone/read-manga/kamisama_to_toberanai_tsukai/ (6.5 chaps; fantasy plot)
http://www.mangago.zone/read-manga/see_you_later_mermaid/ (6 chaps; unique plot)
http://www.mangago.zone/read-manga/lonely_to_organdy/ (5 chaps; one of my all time favs)
http://www.mangago.zone/read-manga/itou_san_kuraka_sui/ (7.7 chaps; a great plot but more mature and dark)
http://www.mangago.zone/read-manga/color_recipe/ (11-ish chaps; a fcked up plot since it’s harada, but i loved it as a darker read)
http://www.mangago.zone/read-manga/hinadori_wa_shiokaze_ni_madoromu/ (8 chaps; 5 star rating)
http://www.mangago.zone/read-manga/kowagaranai_de_soba_ni_ite/ (7 chaps; amnesia)
http://www.mangago.zone/read-manga/ganbare_nakamura_kun/ (11 chaps; no massive plot, but it’s so wholesome)
no clue what you’ve already read/like so i just shoved in a variety; hope this somewhat helps :)
Any must read yaoi that's completed and short, like 1-2 volumes or 6-12 chapters? Something with good plot, thx.