We've all reached that point in our stories where you feel like quitting. You're inner editor is screaming bad things about your plot, that you'll never published, and all the other things your inner editor likes to go about. Give up. Quit. Walk away now. You're not cut out for this kind of work.
My inner editor particularly likes to rant about the plot, or rather the lack of one. Sometimes I listen, tie up a few loose ends, do a little house-keeping, but the thing is it just keeps talking. And if I keep listening, it will eventually drown out my character's voices and then comes a whole new wave of horrible.
You are the writer, the goddess/high spirit/dictator of your story and you make the decisions. Don't ever forget that. Yes, sometimes the inner editor is helpful, sometimes that little bit of niggling doubt in the back of your mind is helpful, but (and it's a big shocker here) sometimes it's not. You have to know when to stop listening and you know what? Go ahead and say it. Shut up, inner editor.
You'd be surprised how well that can work. Some people imagine it being locked away or vacationing to Canada, whatever works, but you have to realize that you are the boss, it's you who decides what happens in the end. Do not quit just because someone tells you to, in your head or in real life, but it doesn't matter what they think. The only opinion that counts is yours.
If it means anything to you, I think you can do it. Actually, I know you can do it. You are a writer, you can do anything.
So the point is, yes, you are going to feel doubtful. Yes, you are going to feel down. Yes, your inner editor is going to rant and rave, but no matter what, never, ever give up.