Greys anatomy

I'm sure I posted about Greys Anatomy when I first started watching but I can't find my original post. 

Anyway I'm in season 6 out of 20. Season 20 has just been added and I'm already wondering how so much happens as I feel a lot has happened for the 6 seasons I've already watched and my friend told me to watch the soon off show also. 

I didn't even know there was a spin off show.