THERE ARE ALWAYS FIRST DRAFT DOUBTS:
I'm assuming all writers have doubts as they are writing the first draft. I know I do. Something happens between the feeling of knowing I have a good plotline and writing out the first draft.
After analyzing it for a while, I believe what happens is that I cannot 'envision' the whole story coming together as I am just blurting out the first half of the first draft.
When writing a first draft, I'm in the nitty gritty now. It's no longer 'thinking about the plotline'. I'm now committing it to paper. A feeling of insecurity arises as I realize that I'm halfway through my scenes and I don't get a feeling of any suspense or mystery. It has absolutely no personality yet. It's dry. The characters are a bit like sticks yet.
THIS IS WHY I START WITH FOUR DIFFERENT PLOTLINES:
Battling against these doubts is one reason I started working on four separate plotlines before choosing the best one. This way, I know I picked the best of four before I even started.
Then I remind myself that a first draft has no details. I'm really more or less linking the scenes where the biggest clues are dropped to one another. In the book I'm writing now, I'm even skipping over most of the subplots until I can get a read on how much "space" I'll have to write them.
What does that mean? It means that as a newer author, I can't go over 80,000 to 100,000 words. So I try to create a first draft with about 45,000 to 60,000. This way, I have room to beef up my subplots, add the descriptions and any theme commentary, etc.
THE DOUBTS ARE MORE ABOUT LACK OF VISION:
The doubts seem to be a combination of an inability to see the final novel and being halfway through the first layer of a first draft. It's hard not to feel that this story is not "good enough". It's not good enough. It's not meant to be good enough. A good enough story needs 8 or 9 layers of writing.
JUST KEEP WRITING:
So the antidote to self-doubt is to keep writing. Trust your plotline. Know too that you can always add clues, rearrange some scenes, add a bit more intrigue into your subplots. Eight layers of writing leaves a lot of room for beefing up a story, deepening a story and polishing a story.
REMIND MYSELF THAT THIS IS ONLY LAYER 3 OF A 7 TO 8 LAYER PROCESS:
I also remind myself that a first draft just has to be gotten through. It's the hardest layer to write because you are writing on faith alone really. You are trusting yourself as a storyteller.