I'm going to be the lone voice of dissent and say that the dress is not suitable for prom. It's a homecoming dress, maybe, but homecoming is more semi-formal whereas prom is formal-the get out the best of everything. It's the last real time before graduation where you will be together with everyone and that calls for FORMAL gowns-you've known some of these people for most of your life and it's a way to really show how elegant you have become. You'd have to get the straps adjusted on that, shorten them up, and maybe alter the very top a bit to make it fit a little better because it seems a little ill-fitting there. I don't want to sound mean, I'm just going off of what the norms are in my area and what is acceptable and not.
Granted, I did not go to my prom-I not only did not get asked, but I was REJECTED by four guys-at the high school I went to, you not only would be looked down upon if you did not have a date, but you also have to be in a group of couples and you have to do the whole dinner-activity-dance-post party thing. I had NO money at the time and my parents would not have been able to help out so it was a moot point there.