From what you have written it appears that the problem is of ineffective communication. You seem to have difficulties in asserting yourself in various situations. The inability to express our thoughts and emotions freely in front of others would certainly create a lot of emotional stress.
It can be frustrating to see ourselves so powerless and out of control.
There are different styles of communication mainly submissive, assertive and aggressive. The most desirable out of the three is assertive behaviour where a person learns to express his thoughts, ideas and opinions without violating the other person’s rights. I would recommend you to seek some professional help in the form of psychotherapy/counselling to enable you to work on your level of self-confidence and become stronger as an individual.