None of those feel very natural to me, I think I would say Ana or Stasi.
Edit: Just saw your comments on the issue, so neither of these would actually work for you. The only thing I can think of for the way you pronounce the name is Stasia, but I’m not sure how to clarify that Stasia is 2 syllables instead of 3.
What trips me up about [name_f]Stasia[/name_f] is that I understand it’s 2 syllables shorter but visually, it doesn’t look that much shorter than [name_f]Anastasia[/name_f] so it doesn’t look like the quick, “I need your attention but your name is too long” name I’m searching for, if that makes any sense!
For your pronunciation, Avonleia is best but I prefer the look of and pronunciation of Avonlea (I’ve always said it similar to how Leanne described but the first A like in cat: ah-von-lee. But I prefer both -lee pronunciations over -leia).
this is how i feel! i’ve always heard and said avonlea with three syllables, so while i don’t like the avonleia spelling as much, it’s probably better for the pronunciation you’re going for