"How do you know if you're any good?"
If you have any passion in you for what is you do, any desire that can not be quenched, so much invested that you deeply care - then I would allow myself the embrace the thought of knowing "I'm good." Now To Be Known is something quite different.
Unfortunately, we can and have created a measuring stick for everything and we carry it in our pocket everywhere we go. We not only use this tangible, narrow, generalizing, incognizant stick for our own work/expressions but we wave it around measuring every one's work around us too. Looking at some of the deeper currents and things in life I doubt you will find, as much as we want to, a means for measuring let alone a value for rating and doing so only hurts the experience.
Try, try your ass off, pause to care, and don't stop there.