help!!! need casual halloween costume ideas!!!

hi! these past few months have been kinda hard for me, long story short i've lost nearly all my friends and i thought that i wouldn't be celebrating halloween this year because of it, and i was really sad because i love halloween. 

however i've been feeling a bit better lately and my bf (almost the only friend i have left) suggested spending halloween with him since he know how much it means to me. i am very exited and i'd like to dress up, but i wasn't able to prepare a costume this year because of how sad i was feeling.

i've got some things in my closet that could maybe be part of a halloween costume (a pleated skirt, a short black summer dress, a nice white button-up shirt...) but i can't reallly think of a character that i can cosplay as with the stuff i have, and i also have very little money to spend.

so please!!! if u have any suggestion of an easy / casual halloween costume, or a character that i can cosplay with the little i have, it would help so much!!!

some last things, i have short brown wavy hair and i don't care about the gender of the character i cosplay, i also like both femenine and masculine outfits. anything helps!!!