I have to agree with Haley and Peachy. I know how hard it is though. When I was down to 150 years ago I still had this image in my head that I was 200 lbs. I remember going into a department store looking for something and had stopped to ask someone where the plus size department was. The girl looked at me in shock and said "baby, those clothes are too big for you." I don't think you ever completely get over the image in my head of me being bigger or that I didn't belong in those clothes.
This is what I can tell you... I have dated men who prefer a girl with a little meat on them. There is someone who will love you for exactly who you are and the size you are. My best friend LOVES a girl with a big ol' booty... His ex wife who was once like a size 4 and then fluxed between 12 and 16 KNEW he loved her regardless.. and he did.
I know exactly how you feel when sizing yourself up against the other girls in the room. Your major insecurity is your size. Did you ever stop to think that you really may have the best personality in the room or the prettiest face? Of course there is initial attraction, but a real man is looking for more than a pretty face... or a nice body because you aren't having a relationship strictly with the body, you have to put up with the person too.
I know many men that say they are attracted to SELF CONFIDENCE... when a woman walks into a room and knows who she is and what she wants... that can be sexier than any girl wearing a size 0 with DD cups. (Does that even exist? LOL)
Love yourself first, that shines brighter than anything else.