The weird thing about pascal's wager is a bit funny. It says "You have nothing to lose, come join us!" yet the only argument made to join specifically christianity instead of literally any other religion is literally
an appeal to popularity. Your religion having the most people in it does not make it any more likely to be true than the religion of any random african tribe. Even if you do "become a christian" solely because of pascal's wager, can you truly say that you actually believe, or are you just saying that you do so that you have a tiny, tiny chance of being saved? I don't know about you, but I don't think any God would appreciate that kind of intellectual dishonesty.
I would just say that there's no perfect agreed upon definition/clarification for the words Atheism and Agnosticism.
Your approach, that of agnosticism being a subset of atheism is one view I've seen, mostly on this website.
It's not just on this website. It is an actual thing, believe it or not. Here's the wikipedia page for it:
https://en.wikipedia.org/wiki/Agnostic_atheismHowever, the curriculum of my A Level Religious Studies course had a different view. That being that;
- Agnosticism is a choice to neither believe there is or isn't a God/gods. It accepts that there could be a deity and therefore isn't atheism.
That seems to directly contradict the definition of atheism.

Of course, if you for some reason
want to make atheism more restrictive (I don't know why you would) then you could use the less broad definition, but that just seems silly to me. By this seemingly generally accepted definition, atheism is
not a belief that no gods exist, but rather a
lack of belief, which allows for the
possibility of one existing. That would be called, as I linked earlier, agnostic atheism. The belief that no god exists on the other hand, would be gnostic atheism. There's also agnostic theism (Theism while admitting the possibility of no gods existing) and gnostic theism. (Theism being absolutely certain that your god exists.) These definitions would make you an agnostic atheist. Nothing wrong with that at all!