I love
Antonia! It's a strong name for a girl. It certainly goes with your other names because of it's historical (ancient
Roman) feel. I know it sounds strange, but I was considering Onia (after the ancient Greek region of Ionia) as a possible nn. I wouldn't dismiss
Toni as a nn too quickly - there is the wonderful author
Toni Morrison as a namesake.
My suggestion as a combo:
Antonia Muse