The advice 'just try be confident' sounds completely useless to you when you feel stuck in life. I've been there and I'm still working through it. It made me mad to hear people say that to me, because I felt I had tried. I made little efforts here and there to changes things about myself and make myself feel better, but they never worked. As a result, I became stubborn. The truth is, the advice is helpful, but I was thinking about it in the wrong way. Confidence isn't something that comes overnight, and it's not reliant upon your appearance. I've accepted that growing my self-esteem is going to be a long task, one I might be doing for most of my life.

The only advice I can give as an add-on is: never make changes for the sake of appealing to others. Make changes for yourself. Pursue what makes you happy, learn things, let yourself grow as a person, have new experiences and you'll begin to feel differently about life. And when you feel better about life, it noticeably changes you - how you carry yourself, how you think and speak, etc - and that makes you more appealing to others.

It's not going to be easy and there will be times when you feel mad at everyone and want to just give up, but the more of those shit moments you survive, the more you'll grow. You will get to a better place than you're at right now but the only person you need to believe in you is yourself. Be your own best friend and learn to love yourself before you expect others to love you. I can't really advise you more because you've got to find your own path - one that's right for you.