I love
Fionnuala, this spelling only. I've never seen your spelling before. You've got the pronunciation correct, though. I'm an Irish-American and would name a dd
Niamh or
Aoife tomorrow, so I'm biased. But
Fionnuala is just gorgeous to my ears.
If your dh doesn't go for it, how about
Finola ("fi-NO-la")? I like just as much as
Fionnuala, but it is more user friendly. And the nn
Nola is so pretty.