Sorry to hear that you're feeling down, Salamander, I know I don't comment much, but you're doing good and solid work.
You've got the skill, the rest's just experience. And you've gotten heaps better since you started out - and you were good to begin with.
It's incredible easy to underestimate the work that goes into illustrating comic, especially when you're just starting out. I know I've done it too. Drawing the pictures itself is relativly easy, but forging them into a cohesive whole, that's where it gets complicated. And yes, half the work's the frigging preperation - which can be very frustrating.
A comic's kinda like a magic trick, it works best when all the prepwork cannot be seen.
How I do it:
When working on ToC, I usually do the panel layout and rough sketches of a whole scene/chapter at once. Only when that's done, I start with the proper drawing. I pencil page per page and panel per panel, but only when I already have the basic layouts including space for speech bubbles completed. I found proper speech-bubble placement important, because they're basically the thread that guides the eye over the page - could be just a personal tick, though.
Granted, I'm doing writing and layout at the same time, but I found it also helps alot when drawing from scripts.
But you know what? You'll suss out a method that works for you, Salamander, simply because a) you're good and learn quick enough and
you've stuck to it for over fifty pages, and those first fifty are the hardest. Most artists would've thrown the towel by now.
*sends hugs*
