I am not an atheist myself, but I often feel backed into a similar sort of corner. If I describe myself as a Christian, people will assume certain things about my beliefs and attitudes that just aren’t true. Similarly, if I say I’m religious, that implies a lot of things that I definitely don’t believe, but not religious or spiritual imply other stuff I also don’t believe. So basically, I’m stuck either coming up with a highly specialized term that doesn’t do any good when trying to succinctly describe my beliefs to others than any of the other more common terms I’ve already rejected, or just going with good enough and then either not really caring what they think or making the effort to explain it to them because it’s worth my effort.
Or as a similar example, we see this same sort of thing with music. Sure, there’s some acts that are just a fairly generic R&B or pop rock or metal whatever, but then there’s a band that, even if what they do is really good, feels like it needs a special label. Using metal, since that’s what I’m most familiar with with this concept, sometimes they come up with some clever name where they’re the only one in their genre, like “sorrow metal” or “movie score metal”, which doesn’t tell you what they actually sound like, or they get so hyper-specific as to be utter nonsense, like avant-garde symphonic blackened death metal. Or they don’t like the history behind a name like black metal or death metal, so they go by “extreme metal” or “unblack metal”. But if I’m stuck explaining these bands to people, I’ll use a better known name, and if they’re familiar with it and interested, they’ll ask for more, and if they’re not familiar, that extra cleverness or specificity is lost on them anyway. And sometimes I’m not interested in saying anything about metal, because they’re clearly not going to be interest (eg, “OMG, have you heard the new Ke$ha?”) or I’m not interested in talking about it, so I just give a minimalist answer.
So to the OP, I just don’t see what’s so bad about the term atheist to you. If you describe yourself as such to someone that is going to believe that atheists are just angry at God and pretend to not believe in him to get back at them, do you think that added specificity about the nuances of what you do and don’t believe is really meaningful to them? And if they are someone who is interested in hearing about the nuances, that’ll be part of the conversation. And, if you don’t want to talk about it, don’t. Find a minimalist answer and move on.
Seriously, for a while I was really into finding specific labels, but that’s when I realized this. No labels offers no information, but too many is just as bad. There’s a nice spot somewhere in between none and lots where they convey useful but not necessarily completely accurate concepts. Sure, inside of a certain context, more specificity is helpful, but as you’ve already eliminated a ton of other possibilities, that greater specificity is now meaningful. So, really, if I were you, I’d not bother. If you say atheist, people will have at least some idea of what you believe, even if it’s not all correct, but if you describe yourself as stoicist, most will ask you what it means, and by the time you explain it, you could have just skipped the label and just explained it.