When you first get into making comics, you need to take into account that you won't make pages as fast as you eventually will when you've built up confidence, "muscle memory" and familiarity with the program you're using and your pipeline for making pages. Even an experienced creator starting a new comic with new characters and maybe a different artstyle or format from ones they've done before will need to allow for early pages taking longer.
My first webcomics didn't look like Errant, they looked like this:

Four panels, literally just pencil, really simple, one character, barely backgrounds... and they still took me a long time and I felt really proud of them when I was sixteen.
This is why everyone is has been saying "you should make a shorter comic first". The frustration of the gap between what you want to be able to create (a big, epic story that looks great, in full colour, updates on a regular schedule and can build an audience) and what you're experiencing (struggling to make pages to that deadline, especially to the level of finish you want) is clearly hurting you, and I can understand why you feel like you want to tear it all down.
I know you have a goal in mind, to finish this comic in a certain timeframe, and I understand it's frustrating to be told "That's not possible right now", but I think you need to spend some time where your sole aim, instead of being "make a comic that updates regularly and builds an audience" should be "Get good at drawing good looking comic pages quickly." Like really focus in on that. Read all the books, watch all the tutorials, do all the drawing exercises you can, and make pages in your own time, without deadlines, but with the aim of each one being a little faster or more polished.
Think of it like running a marathon. It's true, you can enter a marathon that's coming up in a week if you don't train at all, and just set off jogging, occasionally running...mostly walking and sometimes stopping, and complete it in very slow time or get set to the medical tent... or you can wait a year to enter next year's marathon, spend the year training and then kick ass and run the whole thing in a few hours. If you put in the time training now, free from all that other stuff like deadlines and promotion, and so have that freedom to stop halfway through a page and go "...the way I'm doing this is super fiddly, does anyone on the forums know a shortcut for this?" and then be able to redo the same page, or apply that knowledge to the next one, and not need to stress over consistency, you can build your comic drawing muscles for the comic you really care about and be able to draw it how you want, and to the deadline you want.