Calculating voltage, current, and impedance values on an old transformer
I'm not sure you can do this using your method.  You are measuring DC resistance which is not fully controlled by the number of turns - the gauge of the wire matters as well. 

Think about two secondary windings - the first with 'n' turns of wire of area 'x' , and another with 2n turns of wire with 2x area.  They would have the same resistance but different turns ratios.

In your case, the low voltage secondaries are likely to have heavier wire (for more current).