I'm no expert in the matter, but I think it's important to keep updating on a schedule, 2-4 pages seems solid. It looks like you've already got a really strong start, I think you just have to keep at it. Based on what I've heard is you just have to keep at it or get lucky.
Also I agree that the sideways page is a bit of a turn off
But you have nice art and I like the story so far, I think you'll start gaining subs as you update more. Good Luck :>