Tight prom dress, crotch visible?

My prom dress is really tight, black and gray stripes, very flattering (when hungry :P) However, I just noticed that.. well... I have a crotch problem. My vagina bulge shows! After shaving, I think it'll still show. Any.. ya know... cinching underwear?? Or other tips??? Has anyone worn a tight dress to prom? I'm worried. Thanks.