The three months thing really narrows the choices. The fastest growing weed I know of outside of auto-flowering is from Kannabia Seeds....it's called Karamelo. It brags of a 6-7 week flower time and 20+ percent THC. I just started five of 'em and there's a link in my signature charting the grow. I've grown Mataro Blue from the same breeder, and if Karamelo is as good, I'll be very happy.