Can you have a hernia with no bulging? if so, would it be revealed on a ct w contrast?

Depends: Small hernias my not show a visible bulge to the patient themself, but a physical examination with a doctor or general surgeon would feel the hernia bulge. A ct scan may or may not see a hernia, and small hernias would likely be difficult to see or not visible while lying down for a ct scan.

Yes: A hernia may be small so that no bulge is seen or felt, but there is pain. An us or ct can reveal if there is a hernia or not.