If you ever had your titers tested, you would most likely show up as having the anti-bodies and being immune to chickenpox. Not everybody exposed to it gets all or any of the symptoms. My daughter had full exposure to chickenpox (played several times with a friend who had it) and so I waited until the expected incubation period. Sure enough she got a fever and when I looked closely I found 2 spots that were questionable as to what they were, and that was it -- she got better. If I hadn't known of her chickenpox exposure I would have said that she never had it. Yet I'm sure that she is now immune. The same goes for measles and mumps -- it depends on the state of your body when you get exposure -- sometimes you get full symptoms and sometimes you fight it off easily with few symptoms.