As I said when I reviewed it, there's not nothing inherently wrong with your comic that leads to low subscribers...
There are plenty of factors that helps you gain subscribers.
For one, the more you upload, the more visible your comic is.
There's also forum activity... Don't be too thirsty, though, but you get the point.
I do a weekly comic strip, I've been here for a few months, and I'm currently at 10 dubs. I'm sure if I put more time into my art, told a more relatable story, uploaded two pages a week instead of one, used a more satisfying, webcomic appropriate formatting style, among many other thing, my growth would be through the roof.
But I do what I do how I do it. I'm just gonna be patient, tell the story I wanna tell, and hopefully people will like it.