Answer:
Yes, it is possible. Allbeit very, very rare, but it has happened before, yes. It is true that some women 'show' more than others; that is the most common symptom: obvious change in shape. If a pregnant woman is not 'showing' then the case is either that her organs have shifted to allow the baby room or that she may have extra fat around the stomach area that disguises the bump (in the case of organ shifting, it is not very healthy for the mother or child). For an estimate as to other symptoms (such as morning sickness, apetite changes, mood swings, appendage swelling,etc.) simply look back at your family's history, for such things do tend to repeat themselves throughout a bloodline.