I agree! I mean JJ's Enterprise has a round exterior bridge but the set looks very oval to me. So does the toy of it by Playmates as well!
Where do you get the idea that the bridge is supposed to be round in the abrams movie? The production designer has stated at least a couple times he made the bridge oval to take advantage of the 2.35 widescreen format, that a round bridge would have looked flat in that format (you can evaluate the accuracy of that comment by viewing past TREK movies, which were all 2.35, though TUC was shot super35 not anamorphic.)
You can presumably reconcile the interior and exterior appearance/shape of bridge by figuring there is some depth or shell around the non-window part, right? Or does it have visible turbo-lifts and such on the outside?