It's very common to feel this way about your own work. Your eye is trained in both a broad sense and in the context of your own work, consequently you see a thousand flaws that a layman couldn't even consider and even an outside expert would likely shrug off. Ira Glass called this "the gap".
The way to move forward is both make the process as enjoyable as possible and also discipline yourself into doing it regularly enough to improve and flourish. I wish you luck.