Stressed To The Max

I am just beyond stressed. I have Prom this Friday and I'm so scared that I fucked up my diet. When I first got my dress, (it was a back up dress we got off of face book so we didn't know it wouldn't fit) it did not fit. I have an extra rib so my chest pok3s out farther then usual. so the dress stopped zipping up in one place. so, I thought losing some weight might help. and I lost only 2 pounds. but when I last tried on my dress, it just barely fit. but I've been stressed and my body has been acting like it's starving. I went out with my friends to eat and every since then, I've been eating so unhealthy. I noticed so now I'm only eating twice a day, and drinking water with lemon slices inside. does anyone, please, have any good tips to loose something quickly? I'm so scared and I can't try my dress on since no one can help me.