New Shortboard

Hi, guys.
Looking to purchase a new shortboard. I'm 5'8", 130 lbs. I'm only 15, so I'll be gaining more weight and might be getting taller. I've worked my way down to a 6'4" which I'm still so-so on, so I'll be riding that quite a bit more till I get it down 100%. What length (and thickness) board should I get? I'd prefer to not get a fish, and I want something that I can be riding for years to come.
I'm going to be looking on my local Craigslist for a board the length of what you guys suggest.
Thanks in advance.
Looking to purchase a new shortboard. I'm 5'8", 130 lbs. I'm only 15, so I'll be gaining more weight and might be getting taller. I've worked my way down to a 6'4" which I'm still so-so on, so I'll be riding that quite a bit more till I get it down 100%. What length (and thickness) board should I get? I'd prefer to not get a fish, and I want something that I can be riding for years to come.
I'm going to be looking on my local Craigslist for a board the length of what you guys suggest.
Thanks in advance.