HI Muddled. Much of what you say hits the nail right on the head.
what a lot of people do is put on a face at social gatherings to hide their real vulnerable self. So in this way, they become confident, intellectual (if they want) and also very fake.
However I feel that your words hold the best way forward:
"I would love to be like you said crazyoval. Not hesitate before speaking, not care if i'm contradicted and always have something to say. I guess it has to come from within .."
Exactly. When you feel it coming from within you, from your heart and your head, you know its really you that you are presenting. It does come, in time. It takes time but don't get down. Bit by bit you can increase your self esteem by trying out things you've never done before for example, just push yourself a little. Try walking into a crowded bar for example. I know it can be tough but ask yourself what can go wrong, especially if you do it somewhere where no one knows you.
"and unless I feel good about myself I won't be able to fake it."
If you feel good about yourself you will be genuine and will be more successful than anyone who has avoided being honest with themselves. Being genuine means that you will be clearer to respond to anything rather than have to filter everything you hear and respond to. that can be exhausting.
"It just seems like I've been trying so hard for so long."
Stop trying and just be yourself
"Maybe I should stop trying and just be."
you got it
"I don't know how to. I still have a lot of unlearning and relearning to do. "
It is overwhelming but take it day by day, get a book to read. Check out Yellowcoaching's articles if you've not done so already. Take a look at my article on self-esteem. Ask more questions.
If you want it, it will be yours
best of luck!! You are a smart cookie.