Re: Extreme depression!!! want to talk it out…
Okay listen, you are only 17!! At your young age, just concentrate on eating healthy, education and having fun. You will NEVER get this time back, NEVER another chance to be 17 when your parents are there for you, paying for all your bills and expenses. If you think you are going to fail, IT IS OKAY!!! Just try again. If you are not getting an admission in a university of your choice, do an extra semester and put in more hard work.
You have your whole life ahead of you: to stress out, to worry, to feel down but now is not the time for it. If you are having trouble, talk to your parents - confide in them. Yea, our parents have crazy high expectations from us but they will hear you out and be more understanding of your problems and concerns. Abhi zindagi main aur bhi baray baray pangay paray hain aagay. Abhi tou party shuru huwi hai. 
About you weight issues, again it doesn’t take much to lose/gain weight. I have spent my entire life hearing that I am too skinny. Right now, I am having some health issues, and every *aera ghaera *tells me it is because I am so skinny. It mostly comes from all the fat people who are trying to lose weight themselves so I have convinced myself that it’s because they’re jealous that I can eat whatever I want and not gain weight. 
You are an individual: every failure, achievement, setback, problem, mistake is going to make your life more enriching. You think all the successful people became successful so easy? Read about them, their stories. The more successful someone is today, the more crap they have had to go through. Only difference is: they didn’t give up, so why are you?
You know why some people are better salesmen than others? They don’t give up! Instead, they find creative ways to be persistent, to be assertive. Whether it be dealing with an angry customer or a customer who does not speak the same language, they try until they make the sale. Once they get what they want, all the trouble is so worth it. So just keep at it, until you get what you want out of your life.