Umm, no. By that definition, you are an agnostic.
Umm, no. That's not what those words mean.
Atheism is a belief statement. To be atheist means that you lack a belief in any god or gods.
Agnosticism is a knowledge statement. To be agnostic, in this context, means that you don't know if any god or gods exist.
You can be an atheist (lacking belief) and also be agnostic (lacking knowledge). An agnostic atheist would not believe in any gods, but also would not claim to know that no gods exist. A gnostic atheist both lacks the belief and claims knowledge that no gods exist.
I am also an agnostic because I realize you can't *prove* there is no god.
You make the exact same mistake the parent makes: Proof or the ability to prove need not enter in to it at all. We're dealing with "that" not "why", after all.