If you feel like nothing you have tried is working, like your efforts have all been wasted, as if you can't go another step forward... you're doing something right.
No one creates a masterpiece overnight. Furthermore, you don't have a clear vision if you don't constantly question your work. A healthy dose of worry and doubt are a sign that you truly care, not that you truly can't.
The key is that just when you reach that pinnacle of emotions, you must push through to the other side. It is when you feel you have absolutely nothing left, that you must rely on faith to forge on.
Success will be there waiting for you- just beyond your fear.