Have you gotten more or less nerdy with time/age?
Leaving a lot of wiggle room for the vague definitions here - I'd say my nerdiness/geekitude has rested at about the same level throughout my life, though my methods of expression have changed.
If I use Greg K's definitions - my dorkitude has reduced greatly since I was a child. So, in many situations, my geekitude is not terribly noticeable.
Is how nerdy/non-nerdy you consider yourself in agreement with how you think others see you?
That depends upon what "others" you're talking about. Folks generally appear different ways to different people - how I look to my friends is different from how I appear to coworkers, and that's different from the way I look to a complete stranger on the street.