I can see a wheat beer finishing in that range. But if you have a hydrometer available, I would use it and see how close you came with the refractometer and Sean's spreadsheet.
That spreadsheet is pretty good, but IIRC, with lower OG beers, it can be a bit off. You had a plenty big beer, so it should be pretty accurate over time by entering you hydrometer readings for a few beers in this range.