Delphine reminds me of dolphins. I think I've given you negative feedback before. It just feels a touch formal and stiff.
Delphina feels slightly less so, but is maybe too flowery for no reason?
Despina is a new name to me. That Desp- gives me an initial connection to desperate which isn't cool. I think the close connection would be q deal breaker for me personally, but that given your struggle with names it might be worth using anyhow. Maybe explain it isn't after her, but that she certainly left you with good feelings about her name?
~Anna~