Colloquially, you are correct, and colloquialisms are included in dictionaries.
Semantically, you are incorrect. A baby is atheist, because atheism literally means they lack belief in gods. Positively asserting there is no God is something else entirely, and is a belief in it's own. Atheism describes the lack of belief, like Asymmetry describes the lack of symmetry and Agnostic describes the lack of knowledge. Atheism does NOT describe a belief that you have but tells you what belief you don't have, Asymmetry does NOT describe what shape something is but tells you what type of shape it is not, and Agnosticism does NOT describe what you know but tells you what you don't know.
Again, I'm sorry that you don't like the negative feelings associated with the word atheist, and you don't even have to identify as an atheist.
But you are one.
Because you lack a belief in gods. You do not have a belief in gods. You are not a theist. Therefore, you are an atheist. (If you are not symmetrical, then you are asymmetrical. If you do not have knowledge (not gnostic), then you are agnostic).