[doktorhladnjak]

That feeling inadequate at times is a "syndrome" makes a normal human behavior into something pathological. There's nothing wrong with you. There's no mental illness here.

It does raise the second question though: why are you pushing yourself to be something you seem to not enjoy at all?

> I feel physically sick and often succumb to feelings of anxiety

This sounds pretty miserable. Are you sure these are the right roles for you to target?