Need advice on new board - I want more turns/speed!

This is a great site with lots of valuable info!
I have been surfing for almost 9 months and have been getting much better. A month ago something clicked and I can angle into the wave and finally get some turns in. However, I need a new board and don't know which size to get yet.
Currently, I ride an 8'4" 3 - 1/4" 21" board and it has been fun. I am approx 190 lbs, 5' 11". I am not out of shape and my paddling is stronger than ever (I surf about 3-5 days a week and have since I started)
Questions:
I was thinking of either a 7'3" or 7'6". Both about 2 5/8" and 20" Is this too small of a board for my size? Is there a size I should get? Is there a method to determine which specs to ride when coming down in board length? My waves are shorter and about knee-waist high on average. I just don't want to blow money and motivation on something that is not right for me.
Anyway, thanks in advance, any info is greatly appreciated.
I have been surfing for almost 9 months and have been getting much better. A month ago something clicked and I can angle into the wave and finally get some turns in. However, I need a new board and don't know which size to get yet.
Currently, I ride an 8'4" 3 - 1/4" 21" board and it has been fun. I am approx 190 lbs, 5' 11". I am not out of shape and my paddling is stronger than ever (I surf about 3-5 days a week and have since I started)
Questions:
I was thinking of either a 7'3" or 7'6". Both about 2 5/8" and 20" Is this too small of a board for my size? Is there a size I should get? Is there a method to determine which specs to ride when coming down in board length? My waves are shorter and about knee-waist high on average. I just don't want to blow money and motivation on something that is not right for me.
Anyway, thanks in advance, any info is greatly appreciated.