Every person who draws doubts him/herself at some point. What separates you out as an artist as opposed to someone who just draws is that you dont let your doubts get in the way and you still draw something. If I have to spend the next 5 years shouting at you that your a great artist then I will.
Either that or take the hint. I only favourite some damned good art nowadays. And I believe that your just as good as some of the published artists.
Okay, that's the 'pep' talk done. Now for the rant: either keep drawing or I'll forcibly disown you. Through a cannon