Well, pregnancy can do some weird things, from what I've heard. There are several instants in which a woman is pregnant, but there really is no changes in their appearances. Thus, you won't be able to tell if they're pregnant or not unless an ultrasound is done on them. & more often than not, those same women are also completely oblivious to the fact that they're pregnant. That is, until labor comes by...
That aside, was your bump huge during your latter stages of your pregnancy?