As alluded to above, your height and frame size do not necessarily correlate- its only one factor, and generally not the most critical one. Heck, even frame size and frame size (from one manufacturer to another) doesn''t correlate. FWIW, I am 5'8" and ride a 50cm Pinarello Paris and a 52cm vintage Pinarello Record (both c-c). The Paris has a 52.5cm top tube, the Record has a 53. Both fit great (the Paris, a little "more great"). If you are planning on spending serious money on a new frame, get a pro fit from someone who really knows what they are doing.
I'm at the other end of the scale. I ride a 56cm Specialized Roubaix Elite with a 56.5cm top tube effective length and it fits great.
Jim