Thank you for your replies everyone! It feels good to get some perspective from people with different view points. Annabeth/Anny is just a pseudonym. The 'y' is much more intuitive in my real nickname because it also appears in my given name.
I should have mentioned it in my original message, but I have tried to correct people. With my one co-worker I see daily I tried to talk to her about it and point out the difference, but nothing changed.
MariaE, I once had a client I worked with several times who insisted on giving me a nickname instead of calling me by my longer, given name like most of them do. The nickname was one I particularly didn't care for, so I started deleting my automatic signature in my emails and signing them with my preferred nickname in a distinct (but not hit-you-over-the-head-obvious) font. After many emails like that he finally seemed to get the message and began calling me what I wanted to be called and spelling it right. I've tried that approach w/ my bosses for a long time, but it hasn't helped either. So I can vouch that it has worked, at least once. But I guess I might as well stop trying that with my bosses now.
After all this time, it does seem like something rather minor to point out to them verbally now. I don't think it would do any good either.
One poster pointed out that many people are just too busy to notice details like that, and that they mean no disrespect, it's just not something they pay attention to v.s. other things. I think that's how my bosses are. One, at least, would probably lose her head if it wasn't attached. It's just the fact that I've been there so long and it's a small company (not that many names to keep track of) and I make a point of getting people's names right, that culminated in it becoming particularly annoying for me. So I just wondered how many other people do make a point of trying to use people's names/nicknames the way they'd prefer (and if I'm the odd ball for caring).
Also, I have let my bosses know how much I dislike the current task they've assigned me, but they seem to be focused on thinking my concerns and (already well-known) dislike toward the new assignment are unfounded. And yes, I've confided a bit in a co-worker from another dept. about my feelings (toward the job not my name) and she basically said that the job changes all the time so the bosses will probably change their minds eventually and I'll be back to doing something else again. I can only hope.
Anyway, thanks again for your feedback everyone! I know I have a tendency to make a big deal out of things that aren't always are and wasn't sure if this was really something that others would care about too (from either perspective, having their name spelled wrong to spelling names).