That isn't too small at all. I'm 5'11", 160 and I ride a 139 and like it better than a larger, heavier board. Wakeboard sizes are based on weight and skill level
Im pretty sure a lot of the top pros like Harley Clifford and Cory teunisen ride 135s
cory rides a 135 and harley rides a 139. both of them are like below 5 5" though. I would say that the bigger the wake you ride, the bigger the board should be. if the wake isn't that big then can get away with a smaller one. If your on cable I would get the biggest one they have for stability on rails.