Excellent advice from Perna, I'm new here and haven't made many posts but as someone who has low self-esteem and is in the process of learning about the nature of it I'll add my two penneth. I really feel for you because I know how bad those feelings can be but please believe me - there is light at the end of the tunnel.

What you are describing sounds like classic low self esteem - you compare yourself unfavourably with your brother, although you are an unique individual and will have your own strengths (you might not believe that right now but if you work on improving your self esteem you will recognise your strengths). You say you don't want to worry your family, but as a mother I can tell you if my son was feeling as you were I would want him to talk to me - no question about it. As they've asked if you are okay, it's quite likely they are worried already & may be just waiting for you to open up to them.

Perna is right about learning to be your own friend, it's all about not being hard on yourself and looking at yourself with a kindlier perspective. I doubt you would be as harsh on another as you are being on yourself - and for the record I don't think you are bad at talking about yourself, I think you conveyed very well the sadness you are feeling right now & it took courage to post about something you find hard to talk about.

My advice to you would be to think about talking to someone you trust, you might find you feel a bit better just sharing how you feel and the people around you will have the chance to support you. If you don't want to do this perhaps you could talk to your doctor, or is there some kind of student support at your school (apologies, not American so not familiar with the system)?