Hi Love,
I would like to ask why has your confidence and self esteem shot down? What is different now than it was before?
Is your weight gain due to boredom or depression or anxiety?
I'm sure even if it was a coed school, you would find girls being competitive about popularity, looks, and other shallow categories. It's funny how you don't see contests on "Who can score the highest on a test" or "Who can do the most thoughtful act of the week" or "Who can read the most books in a term". That's because many girls are soooo insecure about themselves that they need to be admired by those around them for narcissistic reasons - 'Narcissism' describes the trait of excessive self-love, based on self-image or ego. This is a trap many girls fall into. It's pretty sad and lame.
You have to trust that your friends will accept you for exactly who you are. When was the last time you thought "I want to be friends with that girl because she is pretty, she's not interesting, fun, or nice but she's pretty". Go out with your friends, HAVE FUN WITH THEM! They are not going to care if you put on a few pounds, THEY ARE YOUR FRIENDS!
What are you nervous about for the upcoming day? How and what people will think of you? Don't give people that much power over you.
Getting a boyfriend is not a matter of being brave, it's about finding a boy who likes you for who you are, not just what you look like.
Keep your chin up Girlie!