It's a nice name, I met one who was a nice person as well. But I'd just spell the nickname Nev, after all the "nev" in
Nevena has nothing to do with "heaven" in Irish, you might as well spell it in the more straightforward and expected way.
Nevena PaulaNevena JulieNevena GloriaNevena GabrielleNevena CatherineNevena OrlyNevena Amalia