I am pretty sure that the calculator that you used is not accurate at high SG. If you read the link that was given with the calculator you used, you will see the
actual equation that calculator uses. It is stated that this is an improvement for high-gravity beers over the simple method Rocky uses. That sounds good, right? High-gravity beer is close to wine, right?
Well, not close enough. The approximations used in the more complex calculator you used begin to break down above an initial SG of about 1.06. (That is plenty high for beer, but not for wine.)
The great irony is that the more complex equation gives WORSE results than the simple equation does for SG's over about 1.06. How do I know this? I went to the source of that "complex" equation:
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It turns out that that "complex" equation is an approximation to an even more complex equation. I plotted all three equations (simple, moderately complex, very complex) for a variety of conditions. I chose an initial SG and then plotted the predicted ABV as a function of final SG. For initial SG's below about 1.05, all formulas gave about the same answer. For higher initial SG's, the results diverged, and the simple formula was actually closer to the most accurate (i.e., most complex) formula than the moderately complex one used in the calculator you used.
For your specific case, intial SG= 1.092, final SG = 1.003, the ABV results are:
simple formula (i.e., similar to Rocky's, but 131.25 is the factor) = 11.68
moderately complex formula (same as your calculator) = 12.52
most accurate = 11.77
Hope that helps!