Agnostics

[wiploc]

@All:

Personally, I define the position "I don't know what to believe" as weak atheism.

A lot of weak atheists would be offended at the notion that they don't know what to believe.  Some of them are emphatic; they'll try to put theists and strong atheists in their place.  Weak atheism, according to these people, is the only reasonable position. 
So, yes, you can personally define weak atheism that way if you want to, but you won't be communicating with other people in terms understood by both. 
If you want to invent a new category--though I don't see the usefulness of that particular category--then it would be nice of you to give the new category a new name, so as to avoid sowing confusion.