Leona Jane Antoinette "
Norton" is lovely and I get absolutely no negative vibes or associations from the combination, even after reading your concerns. I think you're good to go. :)
My own initials spell my nickname, which happened by accident. My parents didn't realize it until they'd finally agreed on a first and middle name and then put it together with the surname. I realized it when I was quite young and always thought it pretty nifty. Not sure I can come up with anything for you, but I'll give it a go...
Kenneth Evander N. "
Ken"
Finnegan Ivor Nicodemus N. "
Finn" - I dunno 'bout this. ;)
Vincent Isaiah N. "
Vin"
Conrad Oliver N. "Con"
Gunnar Ulysses N. "Gun"
Jonathan Ozias N. "
Jon"
Solomon Orlando N. "Son"
Winifred Ione N. "Win"
Annabel Naomi N. "
Ann"
Constance Ophelia N. "Con"
Genevieve Estella N. "Gen"
Henrietta Esme N. "Hen"
Juniper Ulyssa N. "
Jun" - does this count?
Lenore Esmeralda N. "
Len"
Penelope Elspeth N. "
Pen"
Wenda Emmeline N. "
Wen"