Would it look sexy or sluty?

So im goin 2 my friends sweet 16 this saturday n i was thinkn i could wear a dress i have one that is: strapless,black, and comes down lke 2 or 3 inches above my knee i wanted 2 wear it with some silver heels...but after i put it on...idk?? should i wear it?? would it look sexy or slutty...i got image of a good girl n ppl think i am one altho im not 1 all da time:) so wat do yall think??or any outfit ideas advise??:)