I'm not entirely sure how accurate this post is with Youtubes new algorithms. Natural growth is certainly a lot harder in the start up stages of your channel. My channel seemed to grow up until around 50 subs then stuck.. I've tried sharing it on forums, facebook, twitter ect I've even got my friends to share the channel, its just doesn't seem to want to grow anymore.
It's slightly soul destroying as I spend almost three hours editing a 4 minute video.. I'm not really sure what else to do. Just keep posting and hoping for the best haha