It's really not that unbeleavable.I didn't show with my DD until a few weeks before I gave birth.If you didn't know my body VERY well you would have never guessed in a million years that I was pregnant.The nurse was like you're only 3 months along or so right? the day I delivered.
I never wore maternity clothes,my boobs weren't huge,and my feet never swelled.
Just think about it...If you were on BC or told that you'd never have kids would you honestly think that you were pregnant?If you had no real symptoms,some spoting,and no reason to think that you were pregnant?
I had a close friend that didn't realize that she was pregnant until she was about 6 months and the only reason she figured it out was the baby moving.She was on the depo shot and didn't think twice about it.She had no morning sickness,a small amount of weight gain which the dr said was normal with the BC,and the dr also told her that breast changes were normal with the BC.Stupid Dr syndrome I guess.