Oh the struggles I have had trying to find my calling in life! or stressing that I don't know what my passion is.
Here is some sound and excellent advice that suggests that instead of worrying about finding our one true 'thing' we should simply pick a path, and develop skills in that area and instead of waiting for divine inspiration to hit, we should uncover interests and commit to developing them over time.
In developing new skills we become more competent and as a result enjoy utilizing these skills
Have a read! its a great article