I see my self as a person with a pretty good developed confidence.

I extremely disagree with the following statement:

''There can be No Room For Self-Doubt''

I would say: ''There MUST be room for Self-Doubt.'' Self-Doubt is very healthy and it could give you better perspective on what you can achieve and what not.
People with no Self-Doubt will try to climb ladders while its almost certain that they will fall-off. I see so many friends of mine doing this.

Examples:

Starting a carrier with to less experience.
Buying a home that you arent able to afford.
Trying to catch the perfect relation.

Guess what? All a product of beeing overconfident and it almost always result in unhappiness and yes.. more self-doubt.