Looking at purchasing a sweet potato ,just not sure on which size .at the moment I surf a speed square (bing) 4'6 with roughly 36ltr of volume great board but not so good on those mushy days when you need a quick take off and not so good when the swell gets a bit bigger.also surf a rake mini simmons 5x22x2 3/4 with a volume of 37ltr so was thinking either 5'6 or5,4 for those onshore days and tiny surf. Been surfing 2 1/2 years 72kg 43years old ,surfing in shitty metro Perth , down the beach 12 hours a week average surfer trying to get better what do you recommend ?