As much as I hate paying retail, mail order shoes are a risky proposition. Not only is there no standardization among mfr.s, but within the same company for a given size. Not sure about cycling, but running shoe fit can vary widely depending on the last. I've bought 2 pr.s of la sportivas, both 10.5Ds. 1 felt like foot binding and my feet were swimming in the others.
As said, feet swell as the day progress, especially if bearing weight. Always recommended to try on new ones late in the day.